a
$Given:F = 100kN = {10^5}N$
$Y = 2 \times {10^{11}}N{m^{ - 2}}$
${\ell _0} = 1.0m$
$radius\,r = 10mm = {10^{ - 2}}m$
$From\,formula,\,y = \frac{{Stress}}{{Strain}}$
$ \Rightarrow \,\,Strain = \frac{{Stress}}{Y} = \frac{F}{{AY}}$
$ = \frac{{{{10}^5}}}{{\pi {r^2}Y}} = \frac{{{{10}^5}}}{{3.14 \times {{10}^{ - 4}} \times 2 \times {{10}^{11}}}}$
$ = \frac{1}{{628}}$
$Therefor\% strain = \frac{1}{{628}} \times 10 = 0.16\% $