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: Egg released by the ovary.
[A]: ovaries


[Q]: Sentence1: Mutations are essential for evolution to occur. 
Sentence2: Genes are altered for evolution to occur.
[A]: evolution


[Q]: Sentence1: if all members of a species cannot produce offspring then that species will likely become extinct. 
Sentence2: The last dodo birds could not produce offspring.
[A]:
offspring