Final answer:
Connective tissue includes various cell types such as fibroblasts, plasma cells, macrophages, and mast cells, which play roles in structure, function, and immunity. Hence, the answer is d) all of these choices.
Step-by-step explanation:
Connective tissue may contain a variety of cell types, including fibroblasts, plasma cells, macrophages, and mast cells. These cells play different roles in maintaining the structure and function of connective tissue. Fibroblasts are the most common cells, responsible for producing the fibrous component of the extracellular matrix.
They are present in all connective tissue proper. The extracellular matrix is composed of ground substance, protein fibers like collagen, and fluid.
Other cell types such as plasma cells, macrophages, and mast cells are also part of connective tissues and participate in the immune response.
These cells can move in and out of the connective tissue, reacting to chemical signals, and contributing to the body's defense mechanisms. Therefore, the correct answer to the question is d) all of these choices.