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: if fossils of a water animal or plant are found in a place then that place used to be covered by water in the past. 
Sentence2: Common fossils include plant fossils like ferns.
[EX A]: plant

[EX Q]: Sentence1: a rainbow is formed by refraction of light by separating light into all different colors. 
Sentence2: Rainbows form when raindrops refract sunlight.
[EX A]: refraction

[EX Q]: Sentence1: Habitat destruction due to human interaction is a problem. 
Sentence2: Human interaction causes animals to move to find shelter in another habitat.
[EX A]:
human