When driving down a long, steep mountain descent in Angola (such as the Serra da Leba pass), what is the safest driving technique to prevent brake failure?

1. Engage a lower transmission gear to utilize engine braking, using foot brakes intermittently to regulate speed
2. Place the transmission into neutral to save fuel and rely solely on continuous foot braking
3. Turn off the ignition engine to prevent overheating
4. Keep the clutch pedal depressed continuously throughout the descent