The correct answer is:
(a) humoral antibody
Explanation:
Congenital agammaglobulinemia is a rare genetic disorder in which the body is unable to produce antibodies, particularly immunoglobulins, due to a defect in B lymphocytes. B cells are responsible for the production of antibodies, which are a key part of the humoral immune response. In individuals with agammaglobulinemia, B cells fail to mature properly, leading to a lack of antibodies (immunoglobulins), which makes the individual highly susceptible to infections.
Correct Answer: (a) humoral antibody