Evolutionary adaptation: a. refers both to the process by which populations become better matched to their environment and to the features of an organism that make it more fit than other individuals. b. cannot occur in environments influenced by humans. c. is possible only when there is no mutation. d. is responsible for the fact that porcupines are at an unusually high risk of predation. e. occurs for physical traits but not behaviors.

answer: - b cells

explanation: -

there are many types of white blood cells present in our body. one such class of white blood cells are the lymphocytes. the b cells belong to the lymphocyte class of wbcs. the b cells perform their action against the pathogen by producing specialised proteins called as antibodies. these antibodies are produced as and when the b cells encounter pathogens in response to the antigens present on the surface of the pathogen. these antibodies bind to the antigens present on the pathogen and then, target them for destruction by other cells of the immune system.

so, the b cells mediate their action by identifying the antigens present on the surface of the pathogens and then producing antibodies in return to mediate its effect.