Which of these is an example of water pollution? A. An eroded hillside
B. A clear-cut forest
C. Arid land
D. Agricultural runoff

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.

the answers are a and c