A truck on a straight road starts from rest and accelerates at 2.3 m/s² until it reaches a speed of 19 m/s. Then the truck travels for 15 s at constant speed until the brakes are applied, stopping the truck in a uniform manner in an additional 3 s. How long is the truck in motion? Answer in units of seconds.
a) 18 s
b) 20 s
c) 22 s
d) 24 s