Following Their Activation, Naive CD4 T Cells Differentiate into One $\gamma$

Following their activation, naive CD4 T cells differentiate into one of several subsets of effector T cells. This developmental choice is determined by which specific cytokines the T cells are exposed to during their activation; in turn, the cytokines that are produced will reflect the nature of the infecting pathogen. In order for this system to be flexible enough to produce all five effector CD4 subsets (T_H1, T_H2, T_H17, T_FH, and iT_reg) :

A) Each naive CD4 T cell must already express one of the lineage-specific transcription factors (i.e., T-bet, GATA-3, etc.) .
B) Each naive CD4 T cell must express all of the STAT proteins.
C) Each naive CD4 T cell must express only a single STAT protein (i.e., STAT1 or STAT6 or STAT3, etc.) .
D) Each naive CD4 T cell must already express low levels of the subset specific cytokines (i.e., IFN $\gamma$ , IL-4, IL-17, etc.) .
E) Each naive CD4 T cell must express all of the lineage-specific transcription factors (i.e., T-bet, GATA-3, etc.) .