Final answer:
T-cells develop in the thymus and are activated in secondary lymphoid tissues, such as the spleen and lymph nodes. The correct answer is b. thymus ; secondary lymphoid tissues. This differentiation is crucial for ensuring T-cells can distinguish foreign antigens without causing an autoimmune response.
Step-by-step explanation:
T-cell development takes place in the thymus, and T-cell activation takes place in the secondary lymphoid tissues. Therefore, the correct answer to the question is b. thymus ; secondary lymphoid tissues.
T-cell maturation occurs after immature T-cells are produced in the bone marrow and migrate to the thymus. In the thymus, they undergo a selection process to ensure that they can recognize foreign antigens without reacting to self-antigens. Following their maturation in the thymus, these naive T-cells then move to secondary lymphoid organs such as the spleen and lymph nodes. It is in these secondary lymphoid tissues that T-cells become activated upon encountering antigens presented by antigen-presenting cells (APCs), thus initiating an adaptive immune response.
B-cells, by contrast, develop and mature within the bone marrow itself, and both B-cells and T-cells arise from hematopoietic stem cells in the bone marrow. This distinction is critical in understanding the organization and function of the body's adaptive immune system.