Please choose the correct ending to complete the given sentence: Cars & Other Vehicles: [header] How to prevent a car from rolling back on a hill [title] Come to a complete stop. [step] When you are on a slope, you need to come to a complete stop using either the brake pedal or the handbrake. This holds true whether you're facing up a slope or down a slope.

Ending1: [substeps] In modern winter conditions, a complete stop is used only if you are approaching a fallen tree branch, as doing so may trigger a car to back up. [title] Make sure you have adequate brake fluid. Ending2: Once you get on the slope, your car will stop as soon as it reaches the top. If you're traveling on a hill, you can try to bring your car to a complete stop at any points where it might start to back up. Ending3: [substeps] Some drivers prefer to use the handbrake, because it frees up their right foot to use on the gas pedal when they intend to start driving again. [title] Use hill-start assist, if available. Ending4: Keeping a straight line will cause you to pull out of something fatal. To avoid falling, keep your shoulders, chin, and head straight ahead and wait for a watch indicator to light up slowly.

Answer format: ending1/ending2/ending3/ending4