Final answer:
Stromal cells in bone marrow produce IL-7, which supports the development of lymphocytes essential for the adaptive immune response(option a).
Step-by-step explanation:
The type of cells in bone marrow that produce IL-7 are stromal cells. IL-7 is primarily used to support lymphocyte development. Therefore, the correct answer to the student's question is A) Stromal cells, supports lymphocyte development.
Interleukin 7 (IL-7) plays a crucial role in the immune system by facilitating the proliferation and differentiation of lymphoid progenitor cells into mature lymphocytes, such as T cells and B cells. These lymphocytes are essential for the adaptive immune response, helping the body to recognize and fight off pathogens.