Answer:
The correct answer to the question: Why is there a long delay between the end of the primary immune response and the beginning of the secondary immune response, would be, C: It takes some time to induce plasma cells to mature into memory cells.
Step-by-step explanation:
The immunological response of the human body to an invasion by a pathogen, or any foreign substance, comes in two parts: the innate response, and the adaptive response. While the first one is simply part of our bodies, and is almost like an emergency, it relies entirely on innate mechanisms, and contact with the invader, to build up a response against it. In the middle of this, and the adaptive response, lies the plasma cells, who are responsible for antibody release. In between the innate response and the building of memory, which is basic for the adaptive immune response, these plasma cells, and T cells, plateau for a time and then they begin the process of differentiation and specialization into memory cells that will, after a while, not need the intermediation of the innate immune response to be able to mount the defensive mechanisms against invading pathogens of the same type. Basically, these memory B and T cells remember the pathogen they were exposed to and will mount a defense as soon as they come into contact with the pathogen itself.