Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.

[Q]: Sentence1: the ovaries are used in reproduction. 
Sentence2: Unlike most female animals, which have two functioning ovaries, the chicken usually has only one.
[A]: ovaries


[Q]: Sentence1: Antibiotics and vaccines are being stockpiled as Britain gears up to meet the bioterrorism threat. 
Sentence2: Antibiotics and vaccines are being stockpiled against another potential threat in the environment.
[A]: Antibiotics


[Q]: Sentence1: an organism requires energy for growth. 
Sentence2: An organism requires energy for a healthy personality.
[A]:
energy