What do we call scientists that study plants?

The answer to this is: A botanist is someone who studies plants.

Explanation:

it's c. (to reduce the greenhouse effect/carbon gasses)

sheep is a herbivore animal whereas grasshopper belongs to the class chordates but both of them feed on greens.  

if grasshopper and sheep feeding on a pasture land, i do not think both of them will have any impact on each other. however, the number of the species can make difference. since sheep feed on greens, there is a possibility there left no pasture land for the grasshoppers or they may get extinct.