What is the wavelength of light emitted by a hydrogen electron that transitions from energy level n?

You would then use the Planck - Einstein equation to get the wavelength of the photon. E =RE⋅1/n21-1/n22), where (btw n∧2∨1 they are exponents.)

RE - the Rydberg constant* expressed in Joules
n1 - the final energy level of the electron
n2 - the initial energy level of the electron

Since you don't have n equalling anything I can't really solve the problem, but that is how you would solve it. :) Hope this helps. 

i guess it’s a and b