The kinetic energy k of a particle moving along a circle of radius R depends on the distance covered s as k = as^2

Hi, I have a question and I hope anyone could answer it:

The kinetic energy k of a particle moving along a circle of radius R depends on the distance covered s as k= as²  where a is a constant. The total force acting on the particle is:

(A) (2afrac{s^2}{R})

(B) 2as (left(frac{s^2}{R^2}right)^{1/2})

(C) 2as

(D) 2as (frac{R^2}{s^2})