The correct option is
D B-cells
Antibody are produced by B-lymphocytes. The plasma cell /plasma B cells/effector B cell are white blood cells that secrete large volumes of antibodies. Plasma cell originates in the bone marrow.B cell differentiate into a plasma cell that produces antibody molecules. These are transported by the blood plasma and the lymphatic system. Once these are released into the blood and lymph, these antibody molecules bind to the target antigen and initiate its neutralization or destruction.
So, the correct answer is 'B-cells'.