Correct Answer  Option 2 : decrease
CONCEPT:

Centripetal Force: The force that makes a body move in a circular motion is known as centripetal force.
 The direction of this force is always perpendicular to the direction of the velocity.
The centripetal force acting on a body of mass 'm' revolving with radius 'r' is:
\(F = {mv^2\over r}\)
EXPLANATION:
Given that the mass and speed of the particle are constant and radius is changing.
So, The centripetal force on the particle \(F = {mv^2\over r}\)
\(F \propto {1\over r}\)
 So as the radius of circular motion increases, the centripetal force on the particle will decrease.
 Hence the correct answer is option 2.