c
$ \mathrm{R} =\frac{\rho \ell}{\mathrm{A}} $
$ \mathrm{R} =\frac{\rho \ell^{2}}{\mathrm{A} \ell}=\frac{\rho \ell^{2}}{\mathrm{V}}$
$\frac{\mathrm{d} \mathrm{R}}{\mathrm{R}}=\frac{2 \mathrm{d} \ell}{\ell} $
${\rm{ Hence, }}\frac{{{\rm{dR}}}}{{\rm{R}}}{\rm{ }} = 1\% $