(A) : When a particle moves in a circle with a uniform speed, its velocity and acceleration both changes.
(R) : The centripetal acceleration in circular motion is dependent on angular velocity of the body.

When a particle moves in a circle with a uniform speed , its direction changes continuously, hence, its velocity and acceleration both changes.

Centripetal force, ${\mathrm{a}}_{\mathrm{c}}={\mathrm{\omega }}^2\mathrm{R}$

Both (A) and (R) are true and (R) is not the correct explanation of (A).