A ball of mass 1.2 kg is attached to a 0.65 m long string. It is moving horizontally in a clockwise direction, 4.0 m above ground, with a speed of 22.0 m/s. The centripetal acceleration of the ball is:

a. 34 m/s²
b. 52 m/s²
c. 160 m/s²
d. 740 m/s²