How did insects become resistant to DDT

A. Some were already resistant and were the survivors that could reproduce.

B. All insects already had genetic resistance to DDT and it took effect once exposed.

C. The gametes of all insects exposed to DDT were mutated for the offspring to be resistant.

D. All surviving insects eventually developed resistance after multiple exposures to DDT.

well, i believe that the answer is 2. : 3

want or the answer

answer;

a. sheep consumption efficiency would be reduced.

explanation;

-trophic efficiency is a measure of how much energy occurs at one level divided by the energy at the level immediately below it . trophic efficiency incorporates three types of efficiency:

-the proportion of available energy that is consumed (consumption efficiency).   it is the proportion of the available biomass that is ingested by consumers.

-the proportion of ingested food that is assimilated (assimilation efficiency).

-the proportion of assimilated food that goes into new consumer biomass (production efficiency).

-in this case, the grasshoppers would affect sheep by reducing the proportion of the available biomass that is ingested by the sheep.