Are these preventative measures a permanent solution? Why or why not?

answer; /// i believe the correct answer is (thrombocytopenia); (a)

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.

this is true, assuming that the allele is completely recessive and incomplete dominance is not a factor.