You are studying a set of mouse genes whose expression increases when cells are exposed to the hormone cortisol, and you believe that the same cortisol-responsive transcriptional activator regulates all of these genes. Which of the following statements believe should be TRUE if your hypothesis is correct?

A. The cortisol-responsive genes share a DNA sequence in their regulatory regions that binds the cortisol-responsive transcriptional activator.

B. The cortisol-responsive genes must all be in an operon.

C. The transcriptional regulators that bind to the regulatory regions of the cortisol-responsive genes must all be the same.

D. The cortisol-responsive genes must not be transcribed in response to other hormones.