$($c$)$ A wire is connected between two buildings a distance $2$ meters apart. The ends of the wire are fixed to the building and cannot move. Let $u(x,t)$ denote the deflection of the wire away from the completely flat$/$straight profile, then the wire satisfies the wave equation

$\frac{de{l}^{2}u}{del{t}^2}-\frac{de{l}^{2}u}{del{x}^2}=0$