If the lower clamp screw is tightened and upper clamp screw is loosened, the theodolite may be rotated

a) on its outer spindle with a relative motion between the vernier and graduated scale of lower plate
b) on its outer spindle without a relative motion between the vernier and gra-duated scale of lower plate
c) on its inner spindle with a relative motion between the vernier and the graduated scale of lower plate
d) on its inner spindle without a relative motion between the vernier and the graduated scale of lower plate
Ans: c