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: Mad Cow disease is a concern. 
Sentence2: pathogens can cause Mad Cow.
[A]: Cow


[Q]: Sentence1: Gravity is a force that pulls on things. 
Sentence2: A force that pulls on things pulls objects towards planets.
[A]: force


[Q]: Sentence1: Most organisms consume--and are consumed by--more than one species. 
Sentence2: An organism is a living creature such as a plant or animal.
[A]:
organisms