Final answer:
The clutch (option A) is what transfers power from the engine to a manual transmission. It allows for engaging and disengaging the engine from the transmission to shift gears. The other options serve different roles in a vehicle's drivetrain.
Step-by-step explanation:
The component that transfers power from the engine to a manual transmission is the clutch. The clutch allows the engine to engage and disengage from the transmission so that the driver can change gears. In a manual transmission, the driver operates the clutch pedal, which connects or disconnects the engine from the transmission. When the clutch is engaged, it creates a physical connection between the engine and transmission, allowing power to flow from one to the other. When disengaged, it interrupts this connection, allowing the driver to change gears without damaging the transmission. The other options listed, such as backing plate, transfer case, and torque converter, serve different purposes in a vehicle's drivetrain.
A backing plate provides a solid mounting for brake components and doesn't play a direct role in power transfer between the engine and the transmission. A transfer case is used in vehicles with four-wheel drive and is responsible for transferring power to both the front and rear axles, while a torque converter is used in automatic transmissions to transfer power and allows the engine to continue running when the vehicle is stopped.