Final answer:
The correct following distance behind a large vehicle or motorcycle is at least two seconds. This provides adequate time to react and helps prevent rear-end collisions.
Step-by-step explanation:
If you are behind a large vehicle or a motorcycle on a high-speed road, your following distance should be at least two seconds. This is often referred to as the two-second rule, which helps ensure that you have enough time to react and stop if necessary. You can measure this by choosing a fixed point that the vehicle ahead of you passes, such as a sign or a tree, and then counting 'one thousand one, one thousand two.' If you reach the same fixed point before you finish counting, you're following too closely.
It's important to maintain a safe following distance because it allows for sufficient reaction time for unexpected events. This is especially crucial behind large vehicles that may obstruct your vision of the road ahead or motorcycles which can stop more quickly than cars. Following too closely can lead to rear-end collisions, which are among the most common types of vehicle accidents.