In automobiles the power is transmitted from gear box to differential through

The correct answer is Option A: Bevel gear.

In automobiles, the power is transmitted from the gearbox to the differential through a bevel gear. Bevel gears are specially designed gears with tapered and conical-shaped teeth that allow the transmission of power at right angles. In this context, they are commonly used in the drivetrain to transfer power from the gearbox to the differential, which further distributes power to the wheels.

Option B: Universal joint is incorrect because universal joints are typically used to transmit power at variable angles, not specifically from the gearbox to the differential.

Option C: Hooke's joint is incorrect as Hooke's joint is another term for a universal joint, which is not the primary component in the described power transmission.

Option D: Knuckle joint is incorrect as knuckle joints are not used for transmitting power in the drivetrain of automobiles.