Self-study
At night, a flock of crows will generally perch close together in a small place—often a piece of wooded land—called a roost. ████ ████████ ███ █████ █████ ███ █████ ███ ███ ███ ██ █████ ██████ ██ ████ ███ ████████ ███ ███████████ █████ ███ ████ ███████ ███ ██████ ███████ ███████ ██ ███ ██ ███ ██ ███ ██████████ ███ ██ ██ ██████ ████ ███ ██████ █████████ █ █████ ████ ████████ ██ ██████ ███ ████ █████ ███ ███████ ███████████ ██████ ███ ████ ██ ████████ █ █████ ████ ███ █ ███ ████ ███ ███ █████ ██ ███████ ████ ████ █████ ██████████ █████ ██████ █████
Summary
At night, a flock of crows will usually perch in a small place called a roost.
Every morning, the crows leave the roost to hunt and scavenge. Most flocks of crows keep their hunting to within 100 to 130 km from the roost.
Normally a flock of crows stays in the same roost for several years.
When a flock abandons a roost to form a new roost, the new roost is usually less than 8 km away from the abandoned roost.
Notable Valid Inferences
There’s no clear inference from the stimulus. I’d rely on process of elimination to identify which answer can most justifiably be rejected.
26.
Of the following claims, which ███ ███ ████ ███████████ ██ ████████ ██ ███ █████ ██ ███ ██████████ ██████
a
Crows will abandon █████ █████ ████ ████ ██ ████████ ██ █████████ ██ ███ ██████████ ██ ███ ██████
No reason to reject. We have no reason to think population changes aren’t requires in order for crows to abandon their roost.
b
When there is █ ████████ ██ ████ ██ ███ ████ ██ █████ █ █████ ██ █████ ████████ █████ ███ ██████████ ████ ███████ ██ ███ █████ ████ █████ ██ ████ ███ ████████ ███████ ████ █████
No reason to reject. Although we know crows typically stay within a certain hunting range, that doesn’t suggest some crows won’t go outside that range.
c
Most of the ███████ ███ ██████████ ████ █████ ██ ██████ ████ ████ █████ ██████████ █████ ██████ ████ █████ ██████
No reason to reject. We know the general range of hunting, but we don’t know anything about where, within that range, crows do most of their hunting and scavenging.
d
Once a flock ██ █████ ███ ███████ ██ █ ███ █████ █████ ██ ██ █████████ █████████ ██ █████ ██ ██ ███████ ████ ████ ███ ████████
No reason to reject. We don’t know anything about the difficulty of getting a flock to abandon a roost.
e
When a flock ██ █████ █████ ██ █ ███ █████ █████ ██ █████████ ████ ██ ███████ ███ ████ ██ █████ ██ ███ ██████ ███ █████████ ███ ████ ████████ ██ ████ ████████
Have reason to reject. When crows move to a new roost, the new one is usually less than 8 km away from the old roost. That means the hunting ranges of the old and new roosts largely overlap. That suggests the crows aren’t motivated by looking for new food sources when they move.