Explanation:
Trees, because of their height, are natural lightning rods. Electricity seeks the path of least resistance, and the moisture inside a tree is a much better conductor than air. This means a tree provides the preferred path for lightning to reach the ground.
First we find the energy level with the following formula, where a is the energy level, n1 is the final energy level, n2 is the starting energy level and r is Rydberg's constant in Joules

We insert the values


The wavelength is found with this formula, where h is Planck's constant and c is the speed of light

Finally we insert the values

Which is the same as 93.8 nm