Which of the following vaccines is recommended for infants at 2 months of age to protect against whooping cough (pertussis)?

Explanation: Passive immunity. Passive immunity is acquired when preformed antibodies are transferred from one individual to another. In this case, the mother's antibodies are transferred to her baby through breast milk, providing temporary protection against certain infections.

Incorrect choices:

a. Active immunity is acquired when the immune system is exposed to a pathogen or vaccination, leading to the production of memory cells and long-term protection.

b. Innate immunity is the body's first line of defense against infections and is not transferred from the mother to the baby but rather present from birth.

c. Adaptive immunity is another term for acquired immunity and involves the production of memory cells after exposure to a specific pathogen or vaccination. It is not transferred through breast milk.

Explanation: The secondary immune response is faster and more potent than the primary immune response due to the presence of memory B cells and memory T cells. These memory cells "remember" the specific antigen from a previous encounter, allowing for a quicker and more effective immune response upon re-exposure to the same antigen.

Incorrect choices:
a. The secondary immune response is faster and stronger compared to the primary immune response, not delayed and weaker.
b. The secondary immune response involves the activation of memory B cells and memory T cells, not naive B cells and T cells.
d. The primary immune response is characterized by the production of IgM antibodies initially, but during the secondary immune response, the production of IgG antibodies predominates, which are more effective in neutralizing antigens.