Final answer:
TFH cells are responsible for activating B cells in germinal centers.
Step-by-step explanation:
TFH cells are a specialized subset of T helper cells that interact with B cells in germinal centers to facilitate the development of high-affinity antibodies.
TFH cells provide help to B cells by releasing cytokines and activating receptors on the B cells, which leads to the production of plasma cells and memory B cells.