A

In uniform circular motion, a particle moves along a circular path with a constant speed. Two key components of motion can be observed: the tangential velocity and the centripetal acceleration.
Step 1: The velocity vector is always tangent to the circular path. Its direction is tangential to the curve at any given point.
Step 2: The acceleration in uniform circular motion is centripetal acceleration, which is directed towards the center of the circular path. This means that while the speed is constant, the direction of motion is continually changing, and thus acceleration is present due to the change in direction.
Step 3: The angle between the tangential velocity vector and the centripetal acceleration vector is measured. Since the velocity is tangential and the acceleration is directed radially inward, the angle between them is 90 degrees.
Conclusion: Therefore, for a particle in uniform circular motion, the angle between the velocity and acceleration is 90 degrees, which corresponds to Option A.