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: threatening behavior by predators causes a porcupine to extend its quills. 
Sentence2: Fishers are predators that can eat porcupines.

A: predators
****
Q: Sentence1: hunting requires seeing prey. 
Sentence2: hunting requires seeing an animal.

A: hunting
****
Q: Sentence1: Plants grow in nutrient rich soil and absorb the nutrients. 
Sentence2: Plants require rich soil to grow.

A:
grow
****