We will individually calculate the Kinetic Energy of each of the carts and compare them
Cart A:
m = 1 kg , v = 3 m/s
KE = 1/2 mv²
KE = 9/2 = 4.5 J
Cart B:
m = 3 kg , v = 1m/s
KE = 1/2 mv²
KE = 3/2 = 1.5 J
Cart C:
m = 3 kg , v = 2 m/s
KE = 1/2 mv²
KE = 6 J
Cart D:
m = 4 kg , v = 2 m/s
KE = 1/2 mv²
KE = 2 J
Therefore, Cart C has the most Kinetic energy