Suppose a magnet is suspended by a vertical string, attached to its middle point. Given that the horizontal component of earth's magnetic field is $25\;\mu T$ and the vertical component of of earth's magnetic field is $40\;\mu T$, find the position in which the magnet can stay in equilibrium.

Question

$\begin{array}{1 1} (A) \theta = \sin^{-1} \large (\frac{8}{5}) \\(B) \theta = \cos^{-1} \large (\frac{8}{5}) \\(C) \theta = \tan^{-1} \large (\frac{8}{5}) \\ (D) \theta = \tan^{-1} \large (\frac{5}{8}) \\ \end{array}$