Answer
(a) No. (b) Yes. (c) Yes. (d) No.
Work Step by Step
(a) The velocity is a vector that is tangent to the rotation. This direction varies upon where you are, so it isn't constant. (b) Since the magnitude of the speed is $v=r\omega$ and the angular speed $\omega$/radius $r$ is constant, the speed must be constant. (c) Since the magnitude of the acceleration is $a=r\omega^2$ and the angular speed $\omega$/radius $r$ is constant, the magnitude of the acceleration must be constant. (d) The acceleration is a vector that points towards the center of the circle. This direction varies upon where you are, so it isn't constant.
