A stone tie with a string held at one end is being rotated at a constant angular velocity in the air. The tangential velocity will remain constant if _______

A stone tie with a string held at one end is being rotated at a constant angular velocity in the air. The tangential velocity will remain constant if _______
 
(a) The plane of motion of the stone is parallel to the ground
 
(b) The plane of motion of the stone is perpendicular to the ground
 
(c) The plane of motion of the stone is at an angle of 45 degrees to the ground
 
(d) The tangential velocity is independent of the plane of motion
 
This question was posed to me by my college professor while I was bunking the class.
 
My question is from Non-Uniform Circular Motion in chapter Laws of Motion of Physics – Class 11
Select the correct answer from above options 
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