A Ball of Mass 5

A ball of mass 5.0 kg is suspended by two wires from a horizontal arm that is attached to a vertical shaft,as shown in the figure.The shaft is in uniform rotation about its axis.The rate of rotation is adjusted until the tensions in the two wires are EQUAL.At that speed,the radial acceleration of the ball is closest to

A) 4.9 m/s².
B) 5.9 m/s².
C) 6.9 m/s².
D) 7.9 m/s².
E) 9.9 m/s².