Final answer:
The steering column is the assembly that uses U-joints, which are flexible couplings that allow for motion transmission at various angles.
Step-by-step explanation:
The assembly that uses U-joints, also known as universal joints, is c) the steering column.
U-joints are commonly used in the steering column to allow the steering wheel to operate smoothly as it transmits motion at varied angles. They are flexible couplings that can transfer the motion at an angle and are crucial for vehicles with rear-wheel drive where the drivetrain is not in a straight line with the wheels. The drag link and tie rod are parts of the steering system that connect the steering gear to the steering knuckle, but they do not use U-joints. The steering wheel itself does not include U-joints, as it is attached to the top of the steering column.