In this task, you are given a sentence and a question, you would be asked to create the answer which is contained in the sentence provided.
Q: Sentence: Studies have shown that not only does reproduction have a cost as far as sperm long male fruit flies live, but also fruit flies that have already mated several times have limited amounts of this. Question: Studies have shown that not only does reproduction have a cost as far as how long male fruit flies live, but also fruit flies that have already mated several times have limited amounts of this?
A:
sperm