Which is a need?
A. shelter
B. gum
C. chocolate bar
D. toys

A-Shelter, the others are for enjoyment while shelter takes care of your physical state

any abiotic or biotic factor in an ecosystem that causes a population's size to slow or decrease is a limiting factor.

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.