A U tube of uniform bore of cross-sectional area A has been set up vertically with open ends facing up. Now m gm of a liquid of density d is poured into it. The column of liquid in this tube will oscillate with a period T such that

• A.            \[T=2\pi \sqrt{\frac{M}{g}}\]
• B.            \[T=2\pi \sqrt{\frac{MA}{gd}}\]
• C.            \[T=2\pi \sqrt{\frac{M}{gdA}}\]                                      
• D.            \[T=2\pi \sqrt{\frac{M}{2Adg}}\]