An excited hydrogen atom returns to ground state. The wavelength of emitted photon is $\lambda$ The principal quantum number of the excited state will be

• A

  ${\left[\frac{1}{\mathrm{\lambda R}(\mathrm{\lambda R}-1)}\right]}^{1/2}$

• B

  ${\left[\frac{\mathrm{\lambda R}-1}{\mathrm{\lambda R}}\right]}^{1/2}$

• C

  $\left[\mathrm{\lambda R}\right(\mathrm{\lambda R}-1){]}^{1/2}$

• D

  ${\left[\frac{\mathrm{\lambda R}}{\mathrm{\lambda R}-1}\right]}^{1/2}$