Question: Amazon offers a generous credit program for college books since they can be resold again to other buyers.
Based on this sentence, who is they?

Answer: college books

Question: There is currently more work on coreference resolution than on chunking because it is a problem that is nearly solved.
Based on this sentence, who is it?

Answer: chunking

Question: The dumpsters arrived each day to retrieve the garbage of the population because they produced a lot of garbage every day.
Based on this sentence, who is they?

Answer: the population

Question: The cops maced the protesters because they blindly follow orders.
Based on this sentence, who is they?

Answer:
The cops