The equation of the curve obtained by reflecting the parabola $y^2=4x$  about the line $x–y+13=0$ is
 

A $(x1,y1)$ be  any point on parabola $y^2 =4x$ and B (h,k) is its image w.r.t x-y+13 = 0 then $\frac{h+x_1}{2}-\frac{k+y_1}{2}+13=0$ and $\left(\frac{k-y_1}{h-x_1}\right)\left(1\right)=-1\Rightarrow x_1=h-13,y_1=-k+13$

$\therefore {(h+13)}^2=4(k-13)$