What is the primary advantage of the memory function in adaptive immunity?
Correct Answer: A
Rationale: The correct answer is A because memory function in adaptive immunity allows for rapid and stronger responses to previously encountered antigens. This is achieved through the presence of memory cells, such as memory B and T cells, which can quickly recognize and respond to specific pathogens upon re-exposure. This leads to a faster and more efficient immune response, providing better protection against future infections.
Choice B is incorrect because direct killing of pathogens without prior activation is a function of innate immunity, not adaptive immunity. Choice C is incorrect as enhanced cytokine secretion is not the primary advantage of memory function. Choice D is incorrect because while memory function provides protection against previously encountered antigens, it does not confer resistance to all infections without exposure.