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: burning fossil fuels increases the carbon in the atmosphere. 
Sentence2: the byproduct of fossil fuels is carbon.
[EX A]: carbon

[EX Q]: Sentence1: Mitosis is cell division. 
Sentence2: mitosis often causes growth.
[EX A]: Mitosis

[EX Q]: Sentence1: boulders are formed by glaciers melting sometimes. 
Sentence2: erratics are formed by glaciers melting.
[EX A]:
formed