An object follows a curved path. The following quantities may remain constant during the

 motion

In curved path, the velocity vector and the acceleration vector changes speed and

  magnitude of acceleration remains constant in case of uniform circular motion.

 (or)

 Options A, D are correct because speed and magnitude of acceleration are scalar physical

 quantities. They may remain constant.

 Options B, C are not correct because those are vector physical quantities. So they change as body moves along on curved path