Final answer:
The question pertains to the operation of magneto ignition systems in aircraft engines, specifically which spark plugs the left magneto fires in a 9-cylinder radial engine. The question lacks sufficient detail to provide a definitive answer.
Step-by-step explanation:
The subject matter of this question revolves around the electrical systems of aircraft engines, specifically the operation of magnetos and the spark plugs they fire in a 9-cylinder radial engine. In such engines, magnetos are responsible for generating the electric current needed for the spark plugs to ignite the fuel-air mixture in the engine cylinders.
Although the question seems to be incomplete, a typical magneto ignition system in aviation may involve each magneto firing a set of spark plugs, either the front or rear ones. However, the question does not provide sufficient context or detail to determine which specific plugs the left magneto will fire in this particular scenario.