Synthesize the process of G protein activation and inactivation in a signaling pathway.

• A. G proteins are activated by ATP binding, leading to downstream signaling, and inactivated by ADP binding.
• B. G proteins are activated by GTP binding, leading to downstream signaling, and inactivated by GDP binding.
• C. G proteins are activated by ADP binding, leading to downstream signaling, and inactivated by ATP binding.
• D. G proteins are activated by GDP binding, leading to downstream signaling, and inactivated by GTP binding.

Answer: (B)