A transcriptional control mechanism would A. modify a protein thereby changing the activity of the protein. B. manipulate the ability of RNA polymerase to carry out its function. C. influence ribosome function. D. result in degradation of a transcript.

B

Explanation:

1. Gene regulation is the process of controlling which genes in a cell's DNA are expressed and finally used to synthesize a functional product such as a protein.

2. Gene expression can be controlled at many steps, like Chromatin accessibility, transcription, RNA processing, post transcription, translation and post translation etc.

3. As at transcription level, it can manipulate the ability of RNA polymerase to carry out its function, which can change the rate of transcription and finally alter gene expression.