Option D is most likely the emission spectrum of oxygen.
What is emission spectrum?
The spectrum of frequencies of electromagnetic radiation emitted due to an electron making a transition from a high energy state to a lower energy state.
What is energy state?
Energy state or energy levels are fixed distances from the nucleus of an atom where electrons may be found.
How do you find the emission spectrum?
We can find emission spectrum using 'diffraction grating.'
by using the diffraction grating we can see the emission spectrum of oxygen shown in image in option D.
Learn more about emission spectrum here -
https://brainly.com/question/2187993
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