C as far as I know. Hope this helps!
Lymphocytes generated during an initial infection that circulate in the body for years and quickly destroy that infection if it ever appears again are called the Memory t cells. These cells are a subset of infection that have previously encountered and responded to their respective antigen, thus they may be called the antigen experienced t cells.
Answer:
Variation, Inheritance, Time and Adaption.
Explanation:
Natural selection is a simple mechanism that causes populations of living things to change over time. In fact, it is so simple that it can be broken down into five basic steps, abbreviated here as VISTA: Variation, Inheritance, Selection, Time and Adaptation.
The theme is the writer's view of or comment about the subject. The answer to your question is D. I hope this is the answer that you are looking for and it comes to your help.