Radius is the halfway point in a circle, the line which says 10 inches. While the diameter is the full length across the circle, which would be the radius times itself, 20.
Step-by-step explanation: We see that it took James 10 minutes to go 0.5 miles, so to get how many miles an hour James is traveling, we need to get the miles to 1. To do this, multiply by 2, and this will give you that it took James 20 minutes to go 1 mile. This is option C.
