Which phrase describes a scientific theory?

C

Explanation:

C. A thoroughly tested and widely accepted explanation. Explanation: A scientific theory is a coherent statement or set of ideas that explains observed facts or phenomenon and are thoroughly tested and widely accepted.

the leaf is an organ of a typical plant, and the main functions are to complete photosynthesis and allow the plant to exchange gas, just like how we have the respiratory system. leaves have the stomata, which collects maintains co2 and o2 levels. this is necessary for cell metabolism. the leaf also collects sunlight using chloroplasts. succinctly, leaves own a pivotal role in sustaining plant life.