Assertion: Foreign bodies in an individual are known as antibodies.

Reason: There are several kinds of white blood cells or leucocytes within the immune system, including T cells, B cells and natural killer cells.

Assertion is false, but the Reason is true.

The immune system relies on the action of white blood cells, also known as leukocytes, to identify and eliminate foreign substances called antigens, such as viruses, bacteria, and other pathogens. White blood cells play a crucial role in the body's defense mechanisms by producing antibodies and directly destroying invaders. Within the immune system, there are different types of white blood cells, including T cells, B cells, and natural killer (NK) cells. T cells are responsible for directly attacking and destroying intruders, while T-helper cells enhance the immune response. T-helper cells are specifically targeted by the Human Immunodeficiency Virus (HIV), which leads to Acquired Immunodeficiency Syndrome (AIDS). B cells, on the other hand, produce antibodies that can recognize and neutralize antigens. NK cells have the unique ability to combat both viruses and tumors, making them an essential component of the immune system's defense mechanisms.