You are riding behind a car that stops suddenly. What technique reduces the risk of a rear-end collision?

1. Riding as close as possible so the car's brake lights give you earlier warning
2. Keeping the clutch disengaged to be ready to change gears quickly
3. Maintaining at least a 3-second following gap so you have enough time to brake progressively
4. Relying on the car's conspicuity to warn vehicles behind them