I really need help with this- 50 points! The secondary messenger cyclic AMP (cAMP) is involved in many different signaling pathways, including the G protein-coupled receptor (GPCR) pathway. Which of the following describes an advantage of using cAMP as a secondary messenger in cell signaling?

A) It conserves energy because cAMP can be converted to ATP
B) It increases signaling specificity because protein kinase A, the direct effector of cAMP, has few substrates
C) It prolongs the signal because cAMP is chemically stable and persists for a long time after ligand dissociation
D) It amplifies the signal because one molecule of activated adenylyl cyclase can produce many molecules of cAMP.