d
In one rotation scale moves $\frac{0.25}{5}=0.05 cm$
Least count $=0.05 \times 10^{-2} cm$
For 4 main scale division $=4 \times 0.05=0.2 cm$
For circular scale divosion $=30 \times 0.05 \times 10^{-2}=1.5 \times 10^{-2} cm$
Thickness of wire $=0.2+0.015=0.2150 cm$