An object travels along a curved path. Which of the following...

For an object moving along a curved path, the direction of motion changes continuously. Since velocity is a vector quantity, a change in direction implies that velocity cannot remain constant.

In uniform circular motion, the object moves along a circular path with a constant speed. The magnitude of its acceleration, given by $\dfrac{v^2}{r}$, also remains constant.

In projectile motion, the object follows a parabolic curved path under the influence of gravity. Throughout the motion, the acceleration is constant in both magnitude and direction ($\vec{g}$ downwards).

Therefore, the speed, acceleration, and magnitude of acceleration may remain constant during motion along a curved path.