Answer: B. Pancreas
Explanation:
Lymphoid organs can be grouped into Primary and Secondary.
Primary Lymphoid Organs include; Thymus and Bone Marrow, responsible for the provision of micro-environments to aid the development and maturation of T-lymphocytes.
Secondary Lymphoid Organs include; Spleen, Peyer's patches of the intestine,Tonsils, Adenoids, Lymph nodes and Appendix. Together, they provide the environment for the interaction of lymphocytes with the antigen, which then multipy to become effector cells.
