Self-study
Two different dates have been offered as the approximate end point of the last ice age in North America. ███ █████ ████ ███ ███████████ ██ ███████ ██████ █████████ █████ ██ ███████ ██ █████████ ██ █████████ ████ ██████████████ ███████████ ███████ ████████ ████████████ ██████ ████████ ███ ██████ ████ ███ ███████████ ██ ███████ ██████ ██████ ██ █████ ████ ███████ ██ █████████ ████ ███ ██████ ███████ ██ ██████ ████████ ███ █████ ████ ██ ████ ████ ███ █████ ███████ ████ ███ ███████
A 500-Year Gap
We have a mini-puzzle. Two different methods have been used to figure out when the last ice age ended in North America, and they produce two different answers.
Method 1 (the beetle method): Scientists looked at insect fragments in sediment samples and identified the moment cold-adapted arctic beetles were replaced by warmth-adapted open-ground beetles.
Method 2 (the spruce method): Using the same samples, scientists looked at pollen grains and identified the moment ice gave way to spruce forests.
The beetle date comes out more than 500 years earlier than the spruce date. So the warmth-adapted beetles showed up first, and the spruce forests followed several centuries later. Each method tracks a different indicator of warming, and the two indicators don't agree on when the ice age ended.
Anticipation
For most Most Strongly Supported questions, it's tough to make a specific prediction. But here we have a clear factual pattern to work with: warmth-adapted beetles established themselves more than 500 years before spruce forests did.
Remember that the standard is comparative. The correct answer just needs to be better supported than the alternatives. Be wary of answers that rely on information the stimulus doesn't give us, or that reverse a timeline the stimulus actually establishes.
7.
The statements above, if true, ████ ████████ ███████ █████ ███ ██ ███ █████████ ███████████ █████ ███ ████ ███ ███ ███ ███ █████████ ██ █████ ████████
a
Toward the end ██ ███ ███ ████ ██████████████ ███████████ ███████ ██████ ██ ███████ █████ █████ ███ ███████████ ████ █████ █████████ ██ ██████ ████████
This claims that warmth-adapted beetles stopped living in areas once spruce forests grew in. The phrase "open-ground" makes this tempting, because you might figure that beetles that thrive in open areas couldn't survive under a forest canopy. But the stimulus doesn't tell us what happened to the beetles after spruce forests arrived. All we know is the order in which things showed up in the sediments. What became of the beetles once the forests moved in isn't something the stimulus speaks to.
b
Among those sediments █████████ ██████ ███ ███ ██ ███ ███ ████ █████ █████ ██ ███████ ████████████ ██████ ██████ █████████ ███ ████ ██ ████████ ██ ███████ █████████████ ███████
This gets the timeline backwards. Cold-adapted arctic beetles are found in the oldest sediments, the ones deposited during the coldest part of the period, before any warming began. Spruce pollen, on the other hand, only shows up in the newest sediments, after spruce forests had established themselves. And by the time spruce forests arrived, the arctic beetles had already been replaced by warmth-adapted beetles more than 500 years earlier.
c
Ice masses continued ██ ███████ ███████ █████ ███████ ███ ███████ ███████ █████ █████ ███ ███ ██ ███ ███ ████
This arguably contradicts the stimulus. We're told that ice masses "yielded to" spruce forests, meaning they retreated. Nothing here suggests ice continued to advance after the ice age ended. The 500-year gap between the two dates isn't evidence of ice advancing; it's evidence that two different indicators of warming (beetles and spruce forests) showed up at different times.
d
The species of ████████████ ██████ ██████ ████ █████████ █████ ███████ ██ ███ ██████ ████ ███ ██████ ███ ███ ██ ███ ████ ███ ████
The stimulus says the arctic beetles were "replaced" in that location, not that they went extinct. The arctic beetles could easily have migrated to colder regions farther north that were still within their temperature range. "Replaced" describes what happened in the sediments being studied; it doesn't speak to whether the species survived somewhere else.
e
Toward the end ██ ███ ███ ████ ██████████████ ███████████ ███████ █████████ ███ ███ ███████ ██████ ██ ████ ██████ ████ ████ ███████ ███ ████ ██████████ ███████████ ███ ██████ ████████
Supported by the 500-year gap. The warmth-adapted beetles showed up in an area, and then it took 500+ years for spruce forests to follow them in. The reason offered by (E), that beetles can colonize new terrain faster than soil changes and seed dispersion can establish a forest, fits this timing well. Beetles fly in and settle quickly; forests take centuries to grow. That's what the data supports.
Note that (E) doesn't have to be proven by the stimulus. It just has to be better supported than the other answers. And it is. No other answer fits the 500-year gap as cleanly as this one.