An Important Way in Which Effector T Cells Differ from Naive

An important way in which effector T cells differ from naive T cells is that _____.

A) the cell-surface level of LFA-1 is lower on effector T cells
B) L-selectin is upregulated during differentiation of effector T cells
C) cellular proliferation occurs after effector T cells leave the secondary lymphoid tissues
D) the provision of co-stimulatory signals is not required to induce a response by effector T cells
E) effector T cells do not recirculate between lymph,blood,and secondary lymphoid tissues.