In which of the following structures does fertilization of an ovum by a spermatozoa occur?

a. Secretes fluid to reduce friction between layers: This is correct. The pleural membranes secrete pleural fluid, which reduces friction between the visceral and parietal layers during breathing.

b. Secretes a substance that reduces surface tension of alveoli: This describes the function of surfactant, which is secreted by alveolar cells, not pleural membranes.

c. Secretes a substance to keep epithelial cells wet: This is a general description that doesn't specifically apply to pleural membranes.

d. Secretes fluid involved in protection from infections: While pleural fluid may have some protective roles, its primary function is to reduce friction, not directly to protect from infections.

a: Contracts and brings about movement - This describes the function of muscle tissue, not connective tissue.

b: Generates and transmits impulses - This describes the function of nervous tissue, not connective tissue.

c: Covers and lines body surfaces - This describes the function of epithelial tissue, not connective tissue

d. Binds tissue together and supports structures: Connective tissue serves to bind, support, and protect other tissues and organs of the body. It also plays a role in insulation, storing energy, and transporting substances.