Least count of screw gauge is defined as

• A

  $\frac{\text{ distance moved by thimble on main scale }}{\text{ number of rotation of thimble }}$

• B

  $\frac{\text{ pitch of the screw }}{\text{ number of divisions on circular scale }}$

• C

  $\frac{\text{ number of rotation of thimble }}{\text{ number of circular scale divisions }}$

• D

  None of the above