# Two wire are made of same material and have same volume However wire 1 has cross-sectional area A and wire 2 has cross-sectional area 3A. If length of wire 1 is increased by $\Delta x$ on applying force F, how much force is needed to stretch wire 2 by same amount
$\begin {array} {1 1} (a)\;4\;F \\ (b)\;6\;F \\ (c)\;9\;F \\ (d)\;F \end {array}$