Write a correct answer to the given question based on its associated fact. Make sure that your answer is contained in the associated fact. Don't be creative and introduce any new word that is not mentioned in the associated fact! Remember that the associated fact has been rearranged to form the question. So, the correct answer words must lie within the associated fact. The correct answer can be a word, phrase, or even a sentence.

[Q]: Fact: protective plates over the ends of the fingers become more brittle with age. 
Question: What do fingers have over the ends that become more brittle with age?
[A]: protective plates.


[Q]: Fact: Plants are essential for cellular respiration for all aerobic organisms. 
Question: What is essential for cellular respiration for all aerobic organisms.?
[A]: Plants.


[Q]: Fact: classification can be based in the evolutionary history of a group of related organisms. 
Question: what can classification be based on?
[A]:
evolutionary past of organisms.