What is one component of the vehicle that directly connects the engine to the transmission?

The driveshaft is a critical component of a vehicle's drivetrain that serves the important function of connecting the engine to the transmission. In a typical auto configuration, the engine generates power, which is then transferred via the transmission to the driveshaft. The driveshaft carries this rotational force to the differential, and ultimately, to the wheels. This ensures that the power generated by the engine can be effectively utilized to propel the vehicle forward.

In contrast, the control arm and ball joint are parts of the vehicle's suspension system and are not involved in the power transfer process. The control arm connects the vehicle's chassis to the wheel assembly, while the ball joint allows for movement and flexibility in the suspension. The piston, on the other hand, is a component within the engine cylinder that compresses the air-fuel mixture for combustion, but it does not play a role in directly connecting the engine to the transmission.

Therefore, the driveshaft is the designated link that carries the engine's power to the wheels, making it the correct answer.