Select the best explanation of how a t cell uses either cell-to-cell contact or chemical signaling to enhance the activities of the immune system.1. chemicals called cytokines are secreted from t cells to signal production of antibodies by b cells.2. the t cell stimulates the antigen-presenting cell to release chemicals called cytokines to stimulate the cytotoxic t cells.3. the second exposure of the antigen causes the t cell to activate memory t cells.4. the pathogen is engulfed by a t cell and its antigenic markers are displayed on its surface.

The correct answer is option 1. "Chemicals called cytokines are secreted from Helper T cells to signal production of antibodies by B cells".

Explanation:

Helper T cells are among the most important cells in adaptive immunity for the role they play at recognizing foreign molecules and enhance the immunity response. Helper T cells enhance the activities of the immune system by synthesizing chemicals called cytokines that serve to signal the production of antibodies by B cells. The cytokines secreted by Helper T cells stimulate the differentiation of B cells into plasma cells, which promote the synthesis of antibodies, and ultimately enhance the immune response.