Final answer:
In humoral immunity, the B cell acts as an antigen-presenting cell and activates a Th cell, which activates the B cell. This process involves the recognition and internalization of an antigen by the B cell, leading to the production of antibodies.
Step-by-step explanation:
In humoral immunity, the B cell acts as an antigen-presenting cell and activates a Th cell, which in turn activates the B cell. This process involves the recognition and internalization of an antigen by the B cell. The B cell then presents the antigen to the helper T cell, which triggers the activation of both cells and leads to the production of antibodies.