The Immunosuppressive Drug Rapamycin Acts by Inhibiting MTOR

The immunosuppressive drug rapamycin acts by inhibiting mTOR. When activated T cells are treated with rapamycin in a cell culture assay, they show greatly diminished proliferation, and accumulate to much lower numbers than control-treated cells. This is because:

A) Rapamycin inhibits cells from increasing their synthesis of lipids and proteins.
B) Rapamycin inhibits cells from activating the pro-survival protein, Bcl-2.
C) Rapamycin inhibits DNA synthesis in activated T cells.
D) Rapamycin inhibits cell cycle progression in activated T cells.
E) Rapamycin inhibits the T cell's production of the growth factor, IL-2.