Why Does Producing a Large "Clone" of Activated T Cells

Multiple Choice

Why does producing a large "clone" of activated T cells also provide long-term immunity?

A) More cells are produced than necessary.
B) Some of the T cells can become B cells.
C) Some of the T cells become memory cells.
D) Leftover antibodies last a long time.
E) The cloned cells are stronger than the original cells.