\(\Pi_1, \Pi_2, \Pi_3\) are three planes which are respectively parallel to the \(Y Z, Z X\) and \(X Y\) planes at distances \(a, b\) and \(c\) forming a rectangular parallelopiped. \(d_1\) is a diagonal of the face of \(X Y\)-plane not passing through the origin and \(d_2\) is a diagonal of the plane \(\Pi_2\) coterminous with \(d_1\). If none of the coordinates of the vertices of the parallelopiped are negative, then the angle between \(d_1\) and \(d_2\) is

1. A \(\cos ^{-1}\left(\frac{a^2}{\sqrt{a^2+b^2} \sqrt{a^2+c^2}}\right)\)
2. B \(\cos ^{-1}\left(\frac{a}{a^2+b^2+c^2}\right)\)
3. C \(\frac{\pi}{2}\)
4. D \(\sin ^{-1}\left(\frac{a^2}{\sqrt{a^2+b^2} \sqrt{b^2+c^2}}\right)\)