Which of the following statements correctly describe gene expression patterns in memory T cells?
a. Activation markers such as CD25 (alpha chain of IL-2 receptor) are upregulated.
b. Expression of Bcl-2, which suppresses apoptosis and promotes cell survival, is increased.
c. Cytotoxic effector molecules (e.g. granzyme B, FasL) are upregulated.
d. All of above