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: burning fossil fuels increases the carbon in the atmosphere. 
Sentence2: the byproduct of fossil fuels is carbon.

SOLUTION: carbon

PROBLEM: Sentence1: All lizards are reptiles. 
Sentence2: Lizards are tetrapod vertebrates that produce amniotic eggs.

SOLUTION: lizards

PROBLEM: Sentence1: For ease of identification, cotton seedlings are classified into the following three categories. 
Sentence2: Protozoa can be identified by how they move.

SOLUTION:
identification