Why Is Bound GTP Considered a "Clock

Multiple Choice

Why is bound GTP considered a "clock"?

A) It behaves in specific time intervals.
B) GTP is exchanged for GDP after binding to adenylate cyclase.
C) The Gɑ receptors have intrinsic GTPase activity, hydrolyzing GTP to GDP and Pi.
D) All of the above.
E) None of the above.