Final answer:
The input shaft in a transmission is driven by the clutch friction disc, connecting the engine power to the transmission.
Step-by-step explanation:
The input shaft is the input to the transmission driven by the clutch friction disc. The input shaft is connected to the engine via the clutch and is responsible for delivering power from the engine to the transmission. When the driver engages the clutch pedal, the clutch friction disc is pressed against the flywheel, which is attached to the engine. This engagement facilitates the transfer of power from the engine to the input shaft and subsequently to the transmission's gearbox for speed and torque adjustments based on driver input through the gear lever.