c
In vertical derection $2 \mathrm{~T} \sin \theta=20$
using small angle approximation $\sin \theta=\theta$
$\theta=\frac{1}{100}$
$\therefore \quad \mathrm{T}=\frac{10}{\theta}$
$T=1000 \mathrm{~N}$
Change in length $\Delta \mathrm{L} \quad=2 \sqrt{\mathrm{x}^2+\mathrm{L}^2}-2 \mathrm{~L}$
$=2 \mathrm{~L}\left[1+\frac{\mathrm{x}^2}{2 \mathrm{~L}^2}-1\right]$
$\Delta \mathrm{L} =\frac{\mathrm{x}^2}{\mathrm{~L}}$
$\therefore$ Modulus of elasticity $=\frac{\text { stress }}{\text { strain }}$
$2 \times 10^{11}=\frac{10^3}{\mathrm{~A} \times \frac{\mathrm{x}^2}{\mathrm{~L}}} \times 2 \mathrm{~L}$
$\therefore \quad \mathrm{A}=1 \times 10^{-4} \mathrm{~m}^2$
