Evaluate the significance of GTPase activity in the G Protein Alpha subunit for resetting the GPCR signaling pathway.

• A. GTPase activity directly increases cytoplasmic calcium levels.
• B. GTPase activity phosphorylates target proteins.
• C. GTPase activity converts DAG into IP3.
• D. GTPase activity is crucial for hydrolyzing GTP to GDP, resetting the signaling pathway.

Answer: (D)