Calculate the Wavelength, in Nanometers, of the Light Emitted by a Hydrogen

Calculate the wavelength, in nanometers, of the light emitted by a hydrogen atom when its electron falls from the n = 7 to the n = 4 principal energy level. Recall that the energy levels of the H atom are given by E_n = -2.18 * 10^-18 J(1/n²)

A) 4.45 * 10^-20 nm
B) 2.16 * 10^-6 nm
C) 9.18 * 10^-20 nm
D) 1.38 * 10¹⁴ nm
E) 2.16 * 10³ nm