The correct answer is option 'C' which is the Balmer series. The Balmer series corresponds to the transitions in the hydrogen atom that result in the emission or absorption of visible light.

The spectrum of the hydrogen atom consists of a series of lines that occur at specific wavelengths. These lines are produced when electrons in the hydrogen atom transition between different energy levels. The different series of lines are named after the scientists who discovered them.

Here's a breakdown of the different series of transitions in the hydrogen atom:

1. Lyman series: This series corresponds to transitions in which the electron jumps from a higher energy level to the n=1 (ground) energy level. The lines in the Lyman series fall in the ultraviolet region of the electromagnetic spectrum and are not visible to the human eye.

2. Balmer series: This series corresponds to transitions in which the electron jumps from a higher energy level to the n=2 energy level. The lines in the Balmer series fall in the visible region of the electromagnetic spectrum, specifically in the range of wavelengths that are visible to the human eye. This is why the Balmer series is the correct answer to the question.

3. Paschen series: This series corresponds to transitions in which the electron jumps from a higher energy level to the n=3 energy level. The lines in the Paschen series fall in the infrared region of the electromagnetic spectrum and are not visible to the human eye.

4. Brackett series: This series corresponds to transitions in which the electron jumps from a higher energy level to the n=4 energy level. The lines in the Brackett series also fall in the infrared region of the electromagnetic spectrum and are not visible to the human eye.

In summary, the transitions in the Balmer series of the hydrogen atom result in the emission or absorption of visible light, making it the only series that falls in the visible region of the electromagnetic spectrum.

Lyman series : UV region