A. the second time a person gets sick from a disease
b. second time immune system encounters an antigen
c. second line of immune defense- the innate immune system
d. the immunity from the adaptive immune system.
The correct answer is b. The secondary immune response refers to the second time the immune system encounters an antigen. During the first encounter, the immune system mounts a primary immune response, and upon subsequent encounters with the same antigen, the immune system produces a faster and more effective response known as the secondary immune response. This is due to the presence of memory cells that remember the specific antigen and can quickly generate the necessary immune response.
