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: 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.
[EX A]: mutation

[EX Q]: Sentence1: Many corals secrete an exoskeleton that builds up to become a coral reef. 
Sentence2: Good examples are Bubble coral, Elegance coral, Frogspawn and other Euphyllia corals.
[EX A]: coral

[EX Q]: Sentence1: Bladder infections can be treated with antibiotics prescribed by a doctor. 
Sentence2: People can be infected or killed by the bacteria.
[EX A]:
infections