A screw gauge has 50 divisions on its circular scale. The circular scale is 4 units ahead of the pitch scale marking, prior to use. Upon one complete rotation of the circular scale, a displacement of $$0.5\,\text{mm}$$ is noticed on the pitch scale. The nature of zero error involved and the least count of the screw gauge, are respectively:

A

Negative, $$2\mu m$$

B

Positive $$10\mu m$$

C

Positive $$0.1\,mm$$

D

Positive, $$0.1\mu m$$