Final answer:
Following distance while driving should be measured in seconds, specifically the 'three-second rule', which adapts to the speed of travel and promotes safe driving habits to avoid traffic accidents.
Step-by-step explanation:
You should always measure your following distance in seconds. This means that when you are driving behind another vehicle, you need to keep a safe distance that allows you enough time to react and stop if necessary. The three-second rule is a common method used for this purpose; however, in adverse conditions such as rain or snow, this should be increased to five seconds or more. Measuring in car lengths can be subjective and vary greatly depending on the speed you are traveling at, and feet or meters are not practical units for driving as they do not account for the speed variance.
A good following distance ensures you have enough time to stop safely without colliding with the vehicle in front should they suddenly brake. Moreover, keeping a proper distance helps prevent traffic accidents and is a key aspect of safe driving practices.
Answer: a. seconds