Which type of white blood cell plays a crucial role in adaptive immunity?

B-cells are a type of white blood cell that plays a vital role in the adaptive immune response. These cells are primarily responsible for the production of antibodies, which are specific proteins that can identify and neutralize foreign pathogens such as bacteria and viruses. When B-cells encounter an antigen, which is any substance that provokes an immune response, they become activated, proliferate, and differentiate into plasma cells that produce large quantities of antibodies. This process not only helps fight off current infections but also contributes to immunological memory, allowing the body to respond more effectively to subsequent exposures to the same pathogen.

In contrast, neutrophils are essential for the innate immune response and primarily deal with acute infections through phagocytosis, but they do not provide the specific, tailored responses seen in adaptive immunity. Erythrocytes, or red blood cells, are involved in oxygen transport and do not play a role in the immune system. Basophils are involved in inflammatory responses and can release histamine, but they are not central to the adaptive immune mechanism.

Thus, B-cells are indispensable for adaptive immunity, marking them as the correct choice in this context.