Where do producers receive its energy?

the sun

Explanation:

Producers tend to be plants and usually act as the base for a food chain/pyramid. Using this plus knowledge about plants and photosynthesis, (the process that plants use to make food/get energy) we can come to the conclusion that producers (plants) get their energy from the sun (using photosynthesis).

i am going to guess that it is co2.

a physical change is being made.