The is the ultimate cause for balancing a population.

age structure

breeding pattern

environment

all of the above

Option D, all of the above

Explanation:

All the demographic components are very essential for balancing the population of any species be it human or animals. The major components of demography are age, sex, average age of mating, average number of children per family, etc.  

All these components of demography/population are affected by environmental conditions. In favorable environmental condition, species/organism mates with each other to produce healthy offspring which could result into a well distributed age structure of the population thereby balancing the population.

Option D, All of the above

blah

explanation:

bc blah

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.