Lymphocytes Are Relatively Abundant,accounting for Approximately 20 Percent of All

Lymphocytes are relatively abundant,accounting for approximately 20 percent of all white blood cells;what is their origin?

A) They are produced by the conversion of other white blood cells,like macrophages,during an infectious event.
B) They originate in the thymus.
C) They are generated in lymph nodes by mitotic division of the cells lining the lymphatic pathway.
D) Like all blood cells,they are produced by the division of stem cells in the bone marrow.