d
\(Y=\frac{\text { Stress }}{\text { Strain }}=\frac{ FL }{ Al }=\frac{ mg . L }{\pi R ^{2} \cdot \ell}\)

\(\frac{\Delta Y }{ Y }=\frac{\Delta m }{ m }+\frac{\Delta L }{ L }+2 \cdot \frac{\Delta R }{ R }+\frac{\Delta \ell}{\ell}\)

\(\frac{\Delta Y }{ Y } \times 100=100\left[\frac{1}{1000}+\frac{1}{1000}+2\left(\frac{0.001}{0.2}\right)+\frac{0.001}{0.5}\right]\)

\(=\frac{1}{10}+\frac{1}{10}+1+\frac{1}{5}=\frac{14}{10}=1.4\, \%\)