Final answer:
HDAC activity is NOT associated with the activation of gene expression but rather with gene repression; HAT activity, transactivators, coactivators, and enhancers are all involved in gene activation.
Step-by-step explanation:
The correct answer to the question regarding RNA pol II promoters and which factor is NOT associated with the activation of gene expression is HDAC activity. HDAC stands for histone deacetylases which are involved in the repression of gene expression by removing acetyl groups from histones, leading to a closed chromatin structure that is not accessible for transcription. On the other hand, HAT activity (histone acetyltransferases), transactivators, coactivators, and enhancers all play a role in activating gene expression by facilitating a more open chromatin structure and promoting the assembly of the transcription initiation complex.