Students are studying the length of time that different battery brands can keep flashlights operating. Which of these should remain constant in this investigation?
A. The length of time
B. The color of the flashlights
C. The type of flashlights
D. The brand of the batteries

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.