The time period of oscillation of a freely suspended bar magnet with usual notations is given by [CPMT 1973, 76, 87; MP PET 1994, 96]

• A.            \[T=2\pi \sqrt{\frac{I}{M{{B}_{H}}}}\]                           
• B.            \[T=2\pi \sqrt{\frac{M{{B}_{H}}}{I}}\]
• C.            \[T=\sqrt{\frac{I}{M{{B}_{H}}}}\]                                    
• D.            \[T=2\pi \sqrt{\frac{{{B}_{H}}}{MI}}\]