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.

[EX Q]: Sentence1: Complex chemistry is needed to carry out all the functions of life. 
Sentence2: Chemistry is primarily concerned with matter, energy, and their interactions.
[EX A]: chemistry

[EX Q]: Sentence1: Every photograph is produced by a camera. 
Sentence2: Photographers record images.
[EX A]: photograph

[EX Q]: Sentence1: Organs of excretion make up the excretory system. 
Sentence2: Excess estrogen is excreted in the bowel.
[EX A]:
excretion