Where do T-lymphocytes and B-lymphocytes mature?

T-lymphocytes mature in the thymus, while B-lymphocytes mature in the bone marrow.

The correct answer is (a) T-lymphocytes mature in the thymus, while B-lymphocytes mature in the bone marrow.

T-lymphocytes, also known as T cells, undergo maturation in the thymus gland, which is a primary lymphoid organ located in the upper chest. The thymus plays a crucial role in the development and selection of T-lymphocytes, leading to the formation of functional T cells that can recognize and respond to specific antigens.

On the other hand, B-lymphocytes, or B cells, mature in the bone marrow. The bone marrow is the site of B-cell development, where immature B cells undergo a series of maturation stages and acquire the ability to produce antigen-specific antibodies.

Option (c) T-lymphocytes maturing in the thyroid and B-lymphocytes maturing in the bone marrow is incorrect. The thyroid gland is involved in the production of hormones and is not associated with lymphocyte maturation.

Option (d) T-lymphocytes maturing in the yellow bone marrow and B-lymphocytes maturing in the red bone marrow is incorrect. The bone marrow contains both red and yellow components, but B-cell maturation primarily occurs in the red bone marrow.

Therefore, the most appropriate combination is (a) T-lymphocytes maturing in the thymus, while B-lymphocytes maturing in the bone marrow.