Answer:
b. end on the n = 2 shell.
Explanation:
When hydrogen atoms move from higher energy level to lower energy level then it shows spectral lines and these lines are known as Balmer series. The only four lines are visible and other liens are not in the visible range.
The Balmer series formed by hydrogen electron and it ends when n = 2.
Therefore the answer is b.
b. end on the n = 2 shell.