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In the winter, ravens survive by eating carcasses; in fact, an individual raven may survive for weeks on one carcass. ████ █████████ ██ ████ ████████ ██████ ████ █████ ███████ ████ ██████ ██ ████ ███ █ ████████ ████ █████████ ██████████ ████████ ██████ █████ ████████ ██ █████ ██████ ██ ██████████████ ██ ███ ██ ███████████ ██████ ████ █████ ██ ███ █ █████ ████ ██ ██ ████ ██████ ██ █████ ██ ██████ █████ ██ █████ ████ ███ █████ ████ ██ ██████ ██ █████ █████████ ███ ██████ ███ ███████ ████ █████████ █████ ██ ███ █████ ███ ██ █████ ███████████ ████████ ████████████ ██ ███ ███ ████ █████████████████ ██ ████████ ██ ██████ █████ ██████ ██ █████ ███ ████████ ████ ████ ████ ███ █████
There were many reports that ravens often recruit more ravens to help eat a carcass. This is counterintuitive, because it seems strange that a raven would be altruistic. Heinrich investigated this phenomenon. He observed a meadow where a mated pair of ravens laid exclusive claim to meat placed by Heinrich. Juvenile ravens had to group up to drive the mated pair away from the meat. (The implication is that ravens might share a carcass not out of altruism, but out of self-interest. The ravens might need to group up in order to access food.)
Describe Method of Reasoning
Heinrich investigated reports of ravens sharing a carcass. He found that this phenomenon might be due to juvenile ravens needing to group up to help get access to food.
15.
Which one of the following ████████████ ████ ████ █████ ██████████ █████ ██ ████████ ██ ███ ███████ ██████
a
He proposed two ███████████ ███████████ ████ ██ █████ █████ ███████ █ ███ ██ █████████████
b
His investigation partially █████████ █████ ████████████ ███ ███ ██ █ ███████ ████████████████ ██ █████ █████████████
c
He proposed a ██████ ███ ████ █████████ ██ ███████ ██ ███████ ████████████
d
He used different ███████ ████ █████ ████ ██ ███████ ███████ ███ ███████ ██ ███ ████ ███████████
e
His investigation replicated ████████ ███████ ███ ███████ █ ████ ███████ ███ ██ █████████████ █████