The figure above depicts the DNA-protein complex that is assembled at the transcriptional start site of gene X when the expression of gene X is activated in liver cells. Previous studies have shown th gene X is never expressed in nerve cells. Based on the diagram, which of the following most likely contributes to the specific expression pattern of gene X? A. Expression of gene X produces large amounts of tRNA but undetectable amounts of mRNA.
B The general transcription factors inhibit the activation of gene X in liver cells by blocking the activator from binding to RNA polymerase II.
С The activator is a sequence-specific DNA-binding protein that is present in some tissues but not in other tissues.
D The enhancer is a unique DNA segment that is added to the nuclear DNA of some cells of an organism during the process of mitotic cell division but not other cells.​