A remote control car races straight down the street at 26 miles per hour. Two
hours later, a second remote control car races straight down the same street
at 52 miles per hour in pursuit of the first car. From the moment the first car
started, how many hours will it take the second car to catch up to the first?

A. Unit conversion
B. Significant figure
C. Estimation/ Scale
D. Comparison of rates of speed