TASK DEFINITION: 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.
PROBLEM: Sentence1: hunting requires seeing prey. 
Sentence2: hunting requires seeing an animal.

SOLUTION: hunting

PROBLEM: Sentence1: a flashlight converts chemical energy into light energy. 
Sentence2: Chemical energy converted to light energy requires batteries.

SOLUTION: chemical

PROBLEM: Sentence1: Marmots live in underground burrows. 
Sentence2: Marmots are protected from a wild fire because they're underground.

SOLUTION:
Marmots