Which one of the following steps would be included in the primary response in humoral immunity?
a. a macrophage consumes a virus and displays antigens on its surface and signals t cells to divide.
b. antigen binds to antibodies.
c. cytotoxic t cells bind to infected body cells and destroy them.
d. t cells activate cytotoxic t cells.

I just took the test from Penn Foster and the answer was Antigen binds with antibodies (B).

yes? sounds right, but you didn’t ask a question.

answer: decrease

a limiting factor is the one which decrease the abundance, distribution and causes extinction of the population of species in a ecosystem. here, predators including hawks, owls and snakes are the limiting factor for the population of mexican free tailed bat.   although bats are nocturnal animals as they forge for food at night these predators also may remain active during night which can decrease the population of the mexican free-tailed bats. also, these bats eat only one type of insects that are moths. the food can also be a limiting factor as all 400 members are dependent upon same type of food needs that are moths. the decrease in the moth population can cause decrease in population size of the mexican free-tailed bats.

therefore, the scenarios will most likely to decrease the population size of the mexican free-tailed bats.