Humans have to eat food to get the nutrients that keep us alive, but plants use the sun to power photosynthesis

Funny! I am doing the same thing. Maybe we can help eachother

Humans have to grow, hunt, and gather food, but many living things aren't so constrained. Plants, algae and many species of bacteria can make their own sustenance through the process of photosynthesis. They harness sunlight to drive the chemical reactions in their bodies that produce sugars. Humans have complicated digestive system and are not designed to use photosynthesis to process their food.

I hope this helped.

substitution is the answer in this case

igneous rocks which formed by the crystallization of magma at the surface of the earth called extrusive rocks. they are characterized by fine-grained textures because the rapid cooling at or near the surface did not provide enough time for large crystals to grow.