Step-by-step explanation:
The centripetal acceleration of the ball that is whirled on the end of a string in a horizontal circle of radius R at constant speed v, is given by :

Option (1) : Keeping the speed fixed and decreasing the radius by a factor of 9


The centripetal acceleration of the ball by a factor of 9.
Option (2) : Keeping the radius fixed and increasing the speed by a factor of 3


Acceleration increases.
Option (3) : Decreasing both the radius and the speed by a factor of 9.


Acceleration decreases by a factor of 9.
Option (4) : Keeping the radius fixed and increasing the speed by a factor of 9


Acceleration increases.
Option (5) : Increasing both the radius and the speed by a factor of 9


Acceleration increases.
Option (6) : Keeping the speed fixed and increasing the radius by a factor of 9


Acceleration increases.
Hence, this is the required solution.