Photosynthesis is important to living organisms because it is a. the foundation of most food chains. b. the source of nitrogen gas in the air. c. how animals get carbon dioxide to breathe. d. the process that occurs in most ecosystems.

The most accurate answer is

***A. The foundation of most food chains.
This is the answer because plant are the main source for the producers in the food chain. In order for them to have plants the process of photosynthesis happens so they can both breath and eat.

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