If \[\theta \] and \[\varphi \] are eccentric angles of the ends of a pair of conjugate diameters of the ellipse \[\frac{{{x}^{2}}}{{{a}^{2}}}+\frac{{{y}^{2}}}{{{b}^{2}}}=1\], then \[\theta -\varphi \] is equal to

• A.            \[\pm \frac{\pi }{2}\]               
• B.            \[\pm \pi \]
• C.            0     
• D.            None of thesew