Self-study
A recent study shows that those highways that carry the most traffic, and thus tend to be the most congested, have the lowest rate of fatal traffic accidents.
"Surprising" Phenomenon
Why do the busiest highways have the fewest fatal accidents?
Objective
Any hypothesis explaining this phenomenon must rely on a difference between the highways carrying the most traffic and other highways. This difference must explain why fatal accidents are less likely on the busiest highways than on other types of highways.
8.
Which one of the following, ██ █████ ████ █████ ██ ███████ ███ ██████████ █████████ ██████
a
Drivers have more █████████ ████ ████ ██████ ███████████
It is not implied whether drivers on the busiest highways are more or less likely to become distracted than drivers on other highways, so this is useless without more information.
b
The highways that ████ ███ ███████ ████ ██ █████ █████████ ████ ████████ ███████ ██ ████████
This adds more detail to the phenomenon without explaining it. It does not address the busiest highways, or explain why they have fewer fatal accidents than other types of highways.
c
Most of the █████████ ██ ████ ███████ ████████ ████████ ████ ██ ██ █████████ ██ ██ ████ █████
It is not implied whether commuters are more or less likely than other drivers to be in a fatal accident, so this is useless without more information.
d
Most serious accidents █████ ████ ████████ ███ ██████ ██ █ ████ ████ ██ ██████
This explains why the busiest highways have the lowest rate of fatal traffic accidents. Because of their congestion, these highways are less likely to carry fast-moving vehicles, and so are less likely to be the site of fatal accidents.
e
Heavily traveled highways ██ ███ ██████ █████ █ ██████ ██████████ ██ █████ ███████
This does not imply that the busiest highways carry fewer trucks than other highways. It allows for the possibility that they often or usually carry a higher proportion of large trucks than other highways.