a ball is whirled on the end of string in a horizontal circe of radius R at constant speed v. the centripetal acceleration on the ball can be increased by factor 4by

A; keeping the speed fixed and increasing the radius by factor 4

B keeping the tradiius fixed by increasing the speed by factor 4

C: keeping the radius fixed and in increasing the period by 4

D: keeping the radius fixed and decreasing the period by 4

E: keeping the speed fixed and decreasing the radius by factor of