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: Ovulation is the release of an egg from an ovary. 
Sentence2: The release of an egg during ovulation is used in reproduction.

A: Ovulation
****
Q: Sentence1: Ozone depletion results in higher levels of UV radiation reaching Earth. 
Sentence2: less ozone means more ultraviolet light.

A: Ozone
****
Q: Sentence1: Carbon cycles quickly between organisms and the atmosphere. 
Sentence2: Carbon dioxide is controlled by the carbon cycle.

A:
Carbon
****