The word medium is used in paragraph 4. Which of the following could be the definition of medium?
A vacuum
Empty space
Anything with molecules; matter
The absence of molecules in an area

Anything woth molecules: matter

Explanation:

because the intervening substance through which impressions are conveyed to the senses or a force acts on objects at a distance.

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.