Answer:
a) sample.
Step-by-step explanation:
When we do research we usually work with populations or samples:
- A population refers to all the elements that belong to a set of data.
- A sample is a subset of said population. In other words, it refers to some elements that belong to the original set.
In this example, at a DUI checkpoint, some cars are stopped at random. We can see that ALL the cars that pass by the checkpoint would be considered the population (since they are all the elements of the set) and the ones that are stopped are SOME elements that belong to the original set, therefore, they can be considered a sample of all the cars that pass by the checkpoint.