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: Energy is the fuel for chemical reactions which run the various systems of the body. 
Sentence2: running requires fuel for chemical reactions which run the various systems of the body.
[A]: body


[Q]: Sentence1: Specialization decreases mortality 12,13 and increases survival. 
Sentence2: evolving different adaptations increases survival.
[A]: increases


[Q]: Sentence1: sexual reproduction increases genetic diversity. 
Sentence2: sexual reproduction allows evolution to continue.
[A]:
reproduction