Which of the following mutations in a gene encoding a transmembrane receptor protein is most likely to create an allele that is completely dominant to a wild-type allele?
A. A missense mutation causes the receptor to be active in the absence of ligands that would normally be needed to activate it.
B. A missense mutation reducing the signaling capabilities of the receptor
C. A deletion of the binding site for a transcription factor that activates expression of the gene
D. A deletion of the entire coding region
