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: pathogens can cause disease. 
Sentence2: pathogens affects the immune system.

Answer: pathogens


Question: Sentence1: Infection is what ultimately leads to death. 
Sentence2: scraping oneself on a contaminated object may cause death.

Answer: death


Question: Sentence1: Zooplankton are tiny animals that feed on phytoplankton. 
Sentence2: Microscopic animals are called zooplankton.

Answer:
animals