Why is the GDP to GTP exchange in heterotrimeric G proteins crucial for adenylate cyclase activation?

• A. It inhibits the binding of epinephrine to GPCR.
• B. It allows the alpha subunit to dissociate and activate adenylate cyclase.
• C. It directly converts ATP into cAMP.
• D. It prevents the activation of protein kinase A.

Answer: (B)