Final answer:
If the power brakes fail due to a loss of engine power, it is recommended to shift into a lower gear and use the emergency brake. The correct multiple-choice option is (1).
Step-by-step explanation:
If the power brakes fail due to a loss of engine power, the recommended course of action is to shift into a lower gear and use the emergency brake. By shifting into a lower gear, you can use the engine's compression to slow down the vehicle, providing some braking power. Additionally, using the emergency brake can help to slow down the vehicle further and bring it to a stop. Pumping the brakes to build up pressure will not be effective if there is a loss of engine power. The correct multiple-choice option is (1).