Which of the following cells is responsible for antigen recognition during the immune response?

Explanation: B cells are a type of lymphocyte that plays a crucial role in the immune response by recognizing and binding to specific antigens. When a B cell encounters an antigen that matches its specific receptor, it becomes activated and differentiates into plasma cells, which produce antibodies against the antigen.

Incorrect choices:

b. Cytotoxic T cells are responsible for directly attacking and killing infected or abnormal cells during cell-mediated immunity. They do not primarily recognize antigens during the immune response.

c. Macrophages are antigen-presenting cells that engulf and process pathogens to present their antigens to other immune cells, such as T cells and B cells. While they are involved in antigen recognition, they are not the primary cells responsible for this function.

d. Red blood cells do not have a direct role in antigen recognition or the immune response. Their primary function is to transport oxygen throughout the body.

Explanation: Active immunity. Active immunity is acquired when the immune system is exposed to a pathogen, either through natural infection or vaccination. It results in the production of memory cells that provide long-term protection against future exposures to the same pathogen.
Incorrect choices:

a. Passive immunity is acquired when preformed antibodies are transferred from one individual to another. It provides immediate but temporary protection and does not involve the production of memory cells.

b. Innate immunity is the body's first line of defense against infections and provides immediate, non-specific protection, but it does not involve the production of antibodies specific to a particular pathogen.

d. Acquired immunity is a general term that includes both active and passive immunity, but it does not specifically describe the type of immunity acquired through vaccination or exposure to a specific pathogen.