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


[Q]: Sentence1: Mollusks live in most terrestrial, freshwater, and marine habitats. 
Sentence2: Clams live in freshwater habitats.
[A]: freshwater


[Q]: Sentence1: Macroevolution occurs over geologic time above the level of the species. 
Sentence2: Species is a property of genus, genus is a property of family, etc.
[A]:
species