Find the parametric form of tangent for the ellipse $\large\frac{x^2}{a^2}+\frac{y^2}{b^2}=$$1$

Question

$\begin{array}{1 1}(a)\;\large\frac{x\cos \theta}{a}+\frac{y\sin \theta}{b}\normalsize=1\\(b)\;\large\frac{x\cos \theta}{a}-\frac{y\sin \theta}{b}\normalsize=1\\(c)\;\large\frac{x\cos \theta}{a}+\frac{y\sin \theta}{b}\normalsize=0\\(d)\;\text{None of these}\end{array}$