The electron transition in a Hydrogen atom can be represented by 4 different colors, which represent different wavelengths and energy. The electron transitions are:
3 -> 2, the color will be red
4 -> 2, the color will be blue-green
5 -> 2, the color will go towards violet
6 -> 2, the color will be violet
Each whole number represents an energy level around the nucleus of the atom
Therefore the option of color that shows the largest electron transition will be the 3rd option, Violet
