Final answer:
The correct answer is C) TFIIA, which is one of the basal transcription factors that does not stay behind at the scaffold after RNA polymerase II leaves the promoter to begin elongation.
Step-by-step explanation:
In eukaryotic gene transcription, basal transcription factors are required for the assembly of the transcription initiation complex, which recruits RNA polymerase II to the DNA template. One of these factors, known as TFIIH, contains subunits with helicase activity, which is crucial as eukaryotic RNA Polymerase II lacks inherent helicase activity. TFIIH is part of the preinitiation complex and plays a role in the phosphorylation of RNA polymerase II, which allows transcription to begin.
When RNA polymerase II leaves the promoter to begin the process of elongation, certain transcription factors dissociate from the initiation complex. Among the choices given in the question, TFIIH and Srb4 (Mediator Head subunit) are typically not known to dissociate at this stage. Therefore, given the options, TFIIA does not stay behind and leaves the scaffold when RNA polymerase II commences elongation.
The correct answer to the question, "Which of the following does NOT stay behind at the scaffold when RNA pol II leaves the promoter to begin elongation?" is C) TFIIA.