Assuming Equal Rates of Acceleration in Both Cases,how Much Longer

Multiple Choice

Assuming equal rates of acceleration in both cases,how much longer would it take a car to stop if braking from 56 mi/h than from 28 mi/h?

A) 8 times as long
B) 4 times as long
C) 2 times as long
D) 1.4 times as long
E) the same in both cases