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: Plants exhibit phototropism, or growing toward a light source. 
Sentence2: Bamboos are vigorous, rugged plants.
[EX A]: Plants

[EX Q]: Sentence1: June Summer Triangle Three bright stars light up the summer sky. 
Sentence2: Nuclear reactions in stars cause them to brighten up the summer sky.
[EX A]: bright

[EX Q]: Sentence1: staying warm has a positive impact on an animal 's survival. 
Sentence2: hydration is needed for survival.
[EX A]:
survival