Uniform Circular Motion:
Uniform circular motion is a type of motion in which an object moves in a circular path at a constant speed. The object's velocity is always tangent to the circular path, and its acceleration is directed towards the center of the circle.

Position Vector:
The position vector represents the current position of the object in the circular path. It is a vector that starts from the center of the circle and points towards the object's current position.

Acceleration Vector:
The acceleration vector represents the object's acceleration in uniform circular motion. It is always directed towards the center of the circle and its magnitude is given by the equation a = v^2/r, where v is the object's speed and r is the radius of the circle.

Explanation of the Correct Answer:
The correct answer is option 'B' - the position vector and acceleration vector are in opposite directions. This means that the position vector and acceleration vector point towards opposite directions in the circular motion.

When an object is in uniform circular motion, its velocity is always tangent to the circular path. This means that the velocity vector is perpendicular to the position vector at any given point in the circular path.

Since acceleration is a vector that represents the rate of change of velocity, it is directed towards the center of the circle. This means that the acceleration vector is perpendicular to the velocity vector and also to the position vector.

Therefore, the position vector and acceleration vector are normal to each other, or in other words, they are at right angles to each other. Since the position vector and acceleration vector are at right angles, they are pointing towards opposite directions.

This can be understood by considering a specific point in the circular path. At this point, the position vector points towards the object's current position on the circle. The acceleration vector, on the other hand, points towards the center of the circle. Since the center of the circle is in the opposite direction of the object's current position, the position vector and acceleration vector are in opposite directions.

Conclusion:
In summary, the correct answer is option 'B' - the position vector and acceleration vector in uniform circular motion are in opposite directions. This is because the acceleration vector is always directed towards the center of the circle, while the position vector points towards the object's current position on the circular path.