Which one of the following statements about T cells involved in an immune response is NOT true? A)Activated T cells receive survival signals from antigen during an infection. B)Activated T cells contribute to the activation of antigen-presenting cells via CD40 ligand. C)Memory T cells generated during a primary immune response express high levels of interleukin-2 receptors and actively proliferate long after the primary response is completed. D)The major effector function of helper T cells is to activate macrophages and other cells by releasing cytokines. E)When an infection is eliminated,activated T cells die by apoptosis.