d
$\text { Least count }=\frac{\text { Pitch }}{\text { No. of circular divisions }}$
$=\frac{0.5\,mm }{100}$
$\text { Least count }=5 \times 10^{-3}\,mm$
$\text { Positive Error }= MSR + CSR ( LC )$
$=0\,mm +6\left(5 \times 10^{-3}\,mm \right)$
$\text { Reading of Diameter }= MSR + CSR ( LC )-$
$\text { Positive zero error }$
$=4 \times 0.5\,mm +\left(46\left(5 \times 10^{-3}\right)\right)-6\left(5 \times 10^{-3}\right)\,mm$
$=2\,mm +40 \times 5 \times 10^{-3}\,mm =2.2\,mm$