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: ultraviolet light causes sunburn. 
Sentence2: Sunburn risk is higher at elevation.
[A]: sunburn


[Q]: Sentence1: Plants use unsaturated fatty acids to store energy. 
Sentence2: Plants and fish contain fatty acids.
[A]: Plants


[Q]: Sentence1: Light enters the eye through an opening called the pupil. 
Sentence2: light is used for seeing ahead.
[A]:
Light