Given a statement and question, generate the answer to the question such that the answer is contained in the statement.
--------
Question: statement: a directory of the types of hemoglobin in the family tree is a useful tool for studying inheritance patterns, question: What is a useful tool for studying inheritance patterns?

Answer: hemoglobin

Question: statement: some therapsids became more mammal-like as they continued to evolve, question: How did some therapsids become?

Answer: mammal

Question: statement: Concealing themselves helps prey avoid being eaten, question: What helps prey avoid being eaten?

Answer:
Concealing