Which of the following is a form of white blood cell involved in the immune response?

Lymphocytes are a specific type of white blood cell that play a crucial role in the body's immune response. They are essential for identifying and attacking pathogens, such as viruses and bacteria. Within the lymphocyte category, there are T cells and B cells, each serving distinct functions in recognizing antigens and coordinating the immune response. T cells help recognize infected cells, while B cells produce antibodies that target and neutralize harmful invaders.

Other options listed, while related to the immune system, do not directly refer to types of white blood cells. Pathogens are the harmful organisms that the immune system targets, vectors are organisms that transmit pathogens to other hosts, and antigens are substances that trigger an immune response, but they are not cells themselves. Thus, identifying lymphocytes as the form of white blood cell involved in the immune response highlights their fundamental role in protecting the body against infections and diseases.