Which method should be used for stopping suddenly in a vehicle without ABS?

Threshold braking is the correct technique to use for stopping a vehicle suddenly when it does not have anti-lock brakes (ABS). This method involves applying enough brake pressure to maximize braking force without allowing the wheels to lock up. By doing so, the driver maintains steering control while effectively reducing speed or coming to a stop.

When a driver uses threshold braking, they modulate the brake pressure to stay just below the point of skidding, which is crucial in a non-ABS vehicle. This allows for better control and traction, ensuring that the vehicle can still respond to steering inputs during an emergency stop.

Panic braking, while described in one of the other options, often involves slamming on the brakes, which can lead to wheel lockup and loss of control. Rapid acceleration is not a braking technique and would obviously not contribute to stopping the vehicle. Drifting to a stop, while sometimes used in motorsports and unique driving scenarios, is not a practical or safe method for passengers or ordinary driving situations, particularly in an emergency. Thus, using threshold braking is the most effective and safest practice for sudden stops in vehicles without ABS.