**Explanation:**

When a body is moving along a circular path, it is constantly changing its direction. This means that its velocity is always changing even if its speed remains constant.

**Constant Speed:**
The speed of an object refers to how fast it is moving. In a circular path, the distance covered by the body in a given time interval remains the same. Therefore, the speed of the body moving along a circular path remains constant.

**Constant Velocity:**
Velocity is a vector quantity that includes both speed and direction. Since the direction of the body moving along a circular path is constantly changing, its velocity is not constant. Therefore, option 'B' is incorrect.

**Radial Acceleration:**
Radial acceleration refers to the change in the direction of velocity. In circular motion, the velocity of the body is constantly changing due to its changing direction. Therefore, there is a radial acceleration acting on the body. Thus, option 'C' is incorrect.

**Tangential Velocity:**
Tangential velocity refers to the velocity of an object in the direction tangent to its circular path. In circular motion, the body is always changing its direction, which means its tangential velocity is not zero. Therefore, option 'D' is incorrect.

**Conclusion:**
From the above explanations, we can conclude that the body moving along a circular path has a constant speed (option 'A') because the distance covered in a given time interval remains the same. However, its velocity, radial acceleration, and tangential velocity are not constant.

Because when you move along a circular path your speed always remains constant and never changes.However its velocity is not constant because the direction keeps on changing continuously in a circular motion however the speed remains the same due to same momentum.