On a global basis, which of the following is the largest reservoir of carbon? atmosphere vegetation sediments fossil fuels

I’m doing some practice exam questions for biology, and i’m not sure how to do these 3 parts to the question.

Biomass can be used to generate electricity. biomass relies heavily on agricultural crops. plants release carbon dioxide and water in combustion. plants use photosynthesis to originally generate the energy that is needed. the chemical energy of these plants all started with what energy source?

Where is the nictitating membrane found? a. between the eyelid and the eyeball b. between the retina and the optic nerve c. between the outer and middle ear d. in the organ of corti in the middle ear