instruction:
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.
question:
Sentence1: Acids dissolve in base and turn blue litmus red. 
Sentence2: acid changes color.
answer:
Acids


question:
Sentence1: Heterotrophs are living things that cannot make their own food. 
Sentence2: food contains organic molecules.
answer:
food


question:
Sentence1: Algae produce oxygen during the day through photosynthesis. 
Sentence2: Plants photosynthesize during the day but not during the night.
answer:

photosynthesis