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.
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Question: Sentence1: After a seed is planted it is watered. 
Sentence2: seeds need water.

Answer: seed


Question: Sentence1: cell division often causes growth. 
Sentence2: Cell division leads to reproduction.

Answer: cell


Question: Sentence1: Ice wedging is the most important form of mechanical weathering. 
Sentence2: cycles of freezing and thawing water causes mechanical weathering.

Answer:
mechanical