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.

Q: Sentence1: Adaptation traits contribute to individual fitness and to the evolution of animal genetic resources. 
Sentence2: Behaviors can improve the evolution of animal genetic resources.

A: animal
****
Q: Sentence1: Carbon dioxide is controlled by the carbon cycle. 
Sentence2: Carbon dioxide is controled by the carbon circle and is transferred between organisms and atmosphere.

A: controlled
****
Q: Sentence1: Like all plants, it needs sunlight and warmth to grow. 
Sentence2: if a tree falls it helps surrounding plants grow.

A:
plants
****