In which situation is the distance traveled proportional to time?

A car moving in stop-and-go traffic

A person biking on a trail at 12
miles per hour for 20

minutes

A baseball hit to center field

A race car slowing down after crossing the finish line

A person biking on a trail at 12 miles per hour for 20 minutes.

The situation in which the distance traveled is proportional to time is when a person is biking on a trail at a constant speed of 12 miles per hour for 20 minutes.