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: Fission is a type of reproduction, but a baby is the result of sexual reproduction. 
Sentence2: the fallopian tubes are used to make babies.
[A]: baby


[Q]: Sentence1: pathogens can cause disease. 
Sentence2: pathogens affects the immune system.
[A]: pathogens


[Q]: Sentence1: Heat transfer always occurs from warm to cool. 
Sentence2: Absorbing sunlight causes cool objects to warm up.
[A]:
cool