Answer:
B. A molecule that causes the body to react negativly to certain substances.
Step-by-step explanation:
Antibody (Ab) also known as immunoglobulin (Ig) is a large Y shaped protein produced by plasma cells. They are used by the body's immune system to neutralize pathogens like harmful bacteria and viruses.
They are secreted by the B cells of the adaptive immune system mostly by differentiated B cells called plasma cells. They are glycoproteins.