What does TT&C stand for and what is its purpose in space missions?

What does TT&C stand for and what is its purpose in space missions?

• A. Telemetry, Tracking, and Command; used to monitor spacecraft health, position, and to issue commands.
• B. Thermal, Timing, and Control; used to regulate spacecraft temperature.
• C. Trajectory, Tracking, and Control; used for ground-based mission planning.
• D. Telemetry, Tracking, and Command; used to calibrate onboard sensors on Earth.

Answer: (D)