Final answer:
CD5 is primarily associated with T cells in the immune system
Step-by-step explanation:
CD5 is primarily associated with T cells in the immune system. CD5 is a cluster of differentiation molecule that is found on the surface of mature T cells and a subset of B cells called B1 cells. It acts as a co-receptor for the T cell receptor (TCR) and is involved in T cell signaling and activation. Therefore, option c) t cells expresses CD5.