If the curves $\frac{x^2}{a}+\frac{y^2}{b}=1$ and  $\frac{x^2}{c}+\frac{y^2}{d}=1$intersect each other at an angle of  $90°$then which of the following relations is TRUE

The given curves   $\frac{x^2}{a}+\frac{y^2}{b}=1,\frac{x^2}{c}+\frac{y^2}{d}=1$intersect orthogonally

The condition that the curves $p{x}^2+q{y}^2=1,p^1{x}^2+q^1{y}^2=1$cuts orthogonally is $\frac{1}{p}-\frac{1}{q}=\frac{1}{p\text{'}}-\frac{1}{q\text{'}}$

Hence, the required condition is $\boxed{a-b=c-d}$