What is the final step after lowering the vehicle back to the ground when changing a tire?

Answer: B — Completely tighten the lug nuts

After lowering the vehicle back to the ground when changing a tire, completely tightening the lug nuts is essential for safety and ensures that the tire is securely attached to the wheel hub. Properly tightening the lug nuts prevents any potential issues, such as the tire coming loose while the vehicle is in motion, which can lead to loss of control or a dangerous situation on the road. Lug nuts should typically be tightened in a crisscross pattern to ensure even distribution of pressure and to avoid warping the wheel. It's also important to ensure they are tightened to the manufacturer’s specified torque, maintaining proper installation standards for optimal performance. Checking the spare tire for pressure is important but comes before the wheel is actually secured. Storing the flat tire in the vehicle is necessary for later repair but is subsequent to ensuring that the spare is safe for travel. Testing the vehicle's engine wouldn’t typically occur until after ensuring all components of the tire change have been completed correctly.