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.
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Question: Sentence1: a mutation in the sex cells of a parent can cause a new trait to appear in the parent 's offspring. 
Sentence2: Traits are initiated by mutation and recombination.

Answer: mutation


Question: Sentence1: An example of a cartilaginous fish is a shark. 
Sentence2: jaws make sharks excellent predators.

Answer: shark


Question: Sentence1: Genetic variation is the raw material for evolution. 
Sentence2: Mutation leads to evolution.

Answer:
evolution