In order to allow gene expression, histone modifying enzymes interact with core histones to modulate their affinity for the DNA and/or other histones, so that specific sequences can be exposed to allow for transcription. From the list below, choose all of the statements that are true.

A) the 'tails' of core histones are an important site for covalent modifications by histone modifying enzymes
B) Histones can be modified in a variety of ways, including methylation, acetylation and phosphorylation.
C) Histones modifications are binary, meaning that modifcations will turn the histone 'on' or 'off'.
D) Histone modifying enzymes can slide the core histones along the DNA without removing it.
E) The H1 histone is sometimes removed, to help expose the DNA for transcription