The answer is: B. Niels Bohr.
Niels Bohr (1885–1962) proposed a model for the hydrogen atom that explained its atomic emission spectrum.
According to the Bohr model of the atom:
1. Energy levels of electrons are discrete (certain discrete values of energy)., that is why hydrogen shows discrete, bright, colored lines.
2. Electrons orbit the nucleus in orbits that have a set size and energy.
3. Electrons can jump from one energy level to another, absorbing or emitting electromagnetic radiation with a frequency ν (energy difference of the levels).