Ans.
B cells or B lymphocytes can be defined as a type of immune cells that function in humoral immune responses. When a non-self, pathogen, such as virus or bacterium, enters to the body, these cells are activated and each B lymphocyte divides to form a plasma cell and a memory cell.
The plasma cell secretes immunoglobulins or antibodies against that particular antigen. These antibodies neutralize the pathogens, which lead to killing and elimination of pathogens from the host body.
Thus, the correct answer is 'antibody.'
