A rainbow for a line spectra from purple through red. There are 5 black lines in purple, 6 black lines in blue, 3 black lines in blue-green, 3 black lines in the green, 6 black lines in the orange and 5 black lines in red.
What is most likely the emission spectrum of oxygen?
I can't give you the letter answer, because all test are different, but it should be the complete opposite of the spectrum shown below, where the blacks are now color and the color are the blacks. For me it was A.