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: Plants exhibit phototropism, or growing toward a light source. 
Sentence2: Bamboos are vigorous, rugged plants.
[A]: Plants


[Q]: Sentence1: creating paper requires cutting down trees. 
Sentence2: Rainforests are destroyed by logging and all of the trees are cut down.
[A]: cutting


[Q]: Sentence1: On the Celsius scale, the freezing point of water is 0 degrees and the boiling point is 100 degrees. 
Sentence2: Water boils when it's heated above 100 degrees.
[A]:
100