[单选题]
A cart starts from rest ana /.c2+f s d.sqp-qgjed accelewra*t ( g6vnp w2yp ae3/4cf1urates at $4.0 \; m/s^2$ for 5.0 s, then maintain that velocity for 10 s, and then decelerates at the rate of $2.0 \; m/s^2$ for 4.0 s. What is the final speed of the car?
