The image shows the Bohr atomic model for oxygen. Oxygen is perhaps the most important atom on Earth. It is responsible for life as we know it, and it is the most abundant atom on our planet. There are more oxygen atoms on Earth than all the other elements’ atoms combined. It was discovered as an atom by Antoine Lavoisier in 1777.

The image shows the Bohr atomic model for oxygen.

Which of the following electronic transitions in the oxygen atom will result in light emission?
A. ni = 1 ⟶ nf = 2
B. ni = 1 ⟶ nf = 3
C. ni = 3 ⟶ nf = 2
D. ni = 2 ⟶ nf = 3