Why was the reduction of the bison population to under 1,000 individuals a bottleneck event for the species?
a. it drastically reduced the gene pool of the species.
b. it reduced the territorial range available to the species.
c. foreign genes were introduced by crossbreeding with cattle.
d. it reduced the prevalence of recessive traits

a. It drastically reduced the gene pool of the species.

The fast reduction in the number of American bison meant that the gene pool of the population decreased as many gene variants were lost. This is called a population bottleneck. It results in a very low level of genetic diversity. In the case of the bison, the change was caused by human activity, but other factors can also cause such reductions in population, such as environmental disaster or habitat destruction that results in the death of living creatures.

so you know what happened be fore you were alive

explanation:

the secretary of state, appointed by the president with the advice and consent of the senate, is the president's chief foreign affairs adviser. the secretary carries out the president's foreign policies through the state department and the foreign service of the united states.