Energy of an electron in nth orbit of hydrogen atom is \[\left( k=\frac{1}{4\pi {{\varepsilon }_{0}}} \right)\] [DCE 2002]

• A.   \[-\frac{2{{\pi }^{2}}{{k}^{2}}m{{e}^{4}}}{{{n}^{2}}{{h}^{2}}}\]        
• B.   \[-\frac{4{{\pi }^{2}}\,m\,k{{e}^{2}}}{{{n}^{2}}{{h}^{2}}}\]
• C.   \[-\frac{{{n}^{2}}{{h}^{2}}}{2\pi \,k\,m{{e}^{4}}}\] 
• D.   \[-\frac{{{n}^{2}}{{h}^{2}}}{4{{\pi }^{2}}\,k\,m{{e}^{2}}}\]