$\begin{array}{1 1}(A)\;1.46\times 10^3N\\(B)\;1.2\times 10^3N\\(C)\;1.36\times 10^3N\\(D)\;\text{None}\end{array} $

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For steel wire

$l_1=1m$

$r_1=1cm=10^{-2}m$

$a=\pi r_1^2$

$Y_1=(\large\frac{F}{a})\frac{l_1}{\Delta l_1}$

$\Delta l_1=(\large\frac{F}{a})\frac{l_1}{Y_1}$

Similarly for copper wire

$\Delta l_2=(\large\frac{F}{a})\frac{l_2}{Y_2}$

$\Delta l_1+\Delta l_2=\Delta l$

$\large\frac{F}{a}(\frac{l_1}{Y_1}+\frac{l_2}{Y_2})=$$\Delta l$

$F=\large\frac{10^{-3}\times \pi\times (10^{-2})^2\times 10^{11}}{(\large\frac{1}{2}+\frac{2}{1.1})}$

$\Rightarrow 1.36\times 10^3N$

Hence (C) is the correct answer.

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