Question

which type of t cell is initially alerted by a macrophage displaying a foreign antigen on its cell surface?
a helper t cell
b cytotoxic t cell
c memory t cell
d natural killer cell

Explanation:

Macrophages act as antigen - presenting cells. They present foreign antigens to helper T cells to initiate the immune response. Cytotoxic T cells target infected or cancerous cells directly. Memory T cells are involved in long - term immunity. Natural killer cells are part of the innate immune system and not a type of T cell in the context of this antigen - presentation process.

Answer:

A. Helper T cell