What is most likely the emission spectrum of oxygen

The last option is correct.

Explanation:

An emission spectrum is that obtained by passing a white light, such as that of the Sun, or of the flame of another element (oxygen, in this case), by a prism and a discontinuous spectrum is obtained. Absorption is when the continuous spectrum passes through another gas and causes the presence of dark lines.

In the case of the options provided, most likely the oxygen emission spectrum is that shown in the last option. This is because, the light pattern, shown in this option is what most resembles the light pattern of the oxygen absorption spectrum.

the fourth option. if you look at it, you just compare the black lines in the diagram for the question with the colored lines for the answer and see which ones match

answer; 60-100; beats per minute