* Uniform motion means an object is moving at a constant speed in a straight line.

Let's break down the options:

* A. The speed of the varies. This is incorrect because uniform motion implies a *constant* speed.

* B. direction velocity constant. This is the definition of uniform motion. Velocity includes both speed and direction. For motion to be uniform, both must be constant.

* C. net force on d? This is incomplete and doesn't make sense in the context of uniform motion. A net force acting on an object would cause acceleration, not uniform motion.

Key Point: If an object is in uniform motion, it means there is no net force acting on it (or any forces are perfectly balanced). This is due to Newton's First Law of Motion (Law of Inertia).