The Transcription Factor PGC-1 $\alpha$ Is Controlled by Two Forms of Covalent Modification

The transcription factor PGC-1 $\alpha$ is controlled by two forms of covalent modification. Which of the following correctly identifies a mechanism of control?

A) phosphorylation by AMPK inhibits PGC-1 $\alpha$
B) dephosphorylation by AMPK activates PGC-1 $\alpha$
C) acetylation by SIRT1 activates PGC-1 $\alpha$
D) deacetylation by SIRT1 activates PGC-1 $\alpha$
E) dephosphorylation by AMPK and deacetylation by SIRT1 activates PGC-1 $\alpha$