What component initiates the burning of a rocket motor in a PGM?

The igniter is the component responsible for initiating the burning of the rocket motor in a Precision Guided Munition (PGM). When the ignition process begins, the igniter generates a specific ignition source that is crucial for starting the combustion of the propellant within the motor. It achieves this typically by producing a spark or by heating up to a temperature that can initiate the chemical reaction of the propellant.

The correct understanding of an igniter’s function is critical, as it ensures a reliable and timely start to the motor's operation, which is essential for the performance and trajectory of the PGM. The igniter is designed to withstand environmental conditions and deliver the exact energy output necessary to start the propellant combustion without any delays or failures.

Connecting this to other potential choices, while the propellant is the actual material that burns to produce thrust, it cannot ignite on its own without the igniter. The detonator serves a different purpose, as it is typically associated with explosives or secondary functions in a munition. Similarly, the throttle controls the thrust level or direction of the rocket once ignited but doesn't initiate the combustion process itself. Therefore, the igniter's role is uniquely pivotal in starting the burn of the rocket motor effectively.