What was one of the first plants to actually look like the common plants that we have today?
a. cooksonia
b. tracheophyta
c. antheridium
d. moss

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 species living around the vents are especially good at dispersal.  

deep-sea vent originates on the floor of the ocean when seawater circulates through hot volcanic rocks, usually situated where the new oceanic crust is being produced.  

biological dispersal refers to the movement of species from their location of birth to their site of breeding, or from breeding site to another. similarly, the oceanic dispersal refers to the movement of the species from one land mass to another by sea crossing.