Find the length of sub tangent and sub-normal for an ellipse $\large\frac{x^2}{a^2}+\frac{y^2}{b^2}$$=1$?

Question

$\begin{array}{1 1}(a)\;\large\frac{a^2}{x_1}\normalsize -x_1,(1-e^2)x_1\\(b)\;\large\frac{a}{x_1}\normalsize- x_1,(1-e^4)x_1\\(c)\;\large\frac{a^2}{x_1}\normalsize+ x_1,(1+e^2)x_1\\(d)\;\text{None of these}\end{array}$