Which term describes the AC ignition system that utilizes transistors?

The term that accurately describes the AC ignition system utilizing transistors is CDI, which stands for Capacitor Discharge Ignition. This system uses a capacitor to store electrical energy, and upon reaching a certain threshold, it discharges this energy through a transistor to create a spark in the ignition coil. The transistors are integral in controlling the electrical flow, ensuring that the timing and energy of the spark are precise, which enhances engine performance and ignition reliability.

Other systems mentioned, such as TDI, refer to different technologies unrelated to AC ignition systems that employ transistors. EFI stands for Electronic Fuel Injection and relates to fuel delivery rather than ignition, while PI refers to Port Injection, which also involves fuel systems. Therefore, the choice that correctly identifies the AC ignition system utilizing transistors is CDI, as it encompasses the essential components and functioning of the ignition process in many engines produced by manufacturers like Yamaha.