A hydrogen atom ia in excited state of principal quantum number `n` . It emits a photon of wavelength `lambda` when it returnesto the ground state. The value of `n` is
A. `sqrt(lambdaR(lambdaR-1))`
B. `sqrt((lambdaR-1)/(lambda))`
C. `sqrt((lambda)/(lambdaR-1))`
D. `sqrt(lambda(R-1))`