
Answer:
n = 3 to n = 2
Explanation:
The Rydberg formula for electron transitions in the hydrogen atom is given by:
1/Îť = Rh( 1/nâ² - 1/nâ² )
where
1/Îť = wavelength of the transition,
Rh = Rydberg constant,
nâ and nâ are the principal quantum numbers of the energy levels involved in the transition with nâ greater nâ.
The energy of the photon is given by
E = hc/Îť
where
h= Planck´s constant
c= speed of light
Therefore the energy is inversely proportional to the wavelength and the term ( 1/nâ² - 1/nâ² )  will be greater  ( 1/2² - 1/3² ) than (1/3² - 1/4² )  ( 0.14 vs 0.05 ). So the transition from n= 3 to n=2 will result in the emission of the highest energy photon in this question.