The correct options are
A Screw gauge is used to measure dimensions of very small objects.
C Screw gauge works under the principle of a screw.
Screw gauge is an instrument used to measure the dimensions of very small objects precisely(up to .01mm).
A screw gauge works under the principle of a screw.When a screw is rotated on a nut, the distance moved by the tip of the screw is directly proportional to the number of rotations.