The diagram shows four horizontal lines representing energy levels of a hydrogen atom. From top to bottom, they are labeled n=4, n=3, n=2, and n=1. To the right of each line, the energy is given in eV: E=−0.85 eV for n=4, E=−1.5 eV for n=3, E=−3.4 eV for n=2, and E=−13.6 eV for n=1. Which of the following electron transitions will cause the atom to emit a photon of energy 1.9 eV?