AMP - Aviation Maintenance Technician Powerplant Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

The primary coil is the correct answer because the secondary coil of a magneto is typically grounded through the primary coil to create an electrical circuit. The ignition switch (A) may control the grounding of the circuit, but it is not directly connected to the secondary coil. The ground side of the breaker points (C) is not connected to the secondary coil and is used to interrupt the primary circuit. The engine's main grounding circuit (D) is connected to the engine and is not specifically linked to the magneto's secondary coil.