A body revolving in circle generally has tangential acceleration if the speed is changing. Since the speed is uniform here, the tangential acceleration is zero.
centripetal acceleration is directed towards the center and is given as
a = v²/r where a = centripetal acceleration , v = speed , r = radius
Since both speed and radius are constant here, the centripetal acceleration is constant and is always directed towards the center.
hence the correct choice is
The acceleration is directed toward the center.