This spectrometer reading shows some red, blue, and purple. our atom is most likely
this spectrometer reading shows some reds, orange, and yellow. our atom is most likely
this spectrometer reading shows some red, yellow, and blue. our atom is most likely
this spectrometer reading shows some yellow, blue, and purple. our atom is most likely

This spectrometer reading shows some red, blue, and purple. Our atom is most likely Hydrogen source.

This spectrometer reading shows some reds, orange, and yellow. Our atom is most likely Neon source. 

This spectrometer reading shows some red, yellow, and blue. Our atom is most likely Helium source.

This spectrometer reading shows some yellow, blue, and purple. Our atom is most likely Mercury source

The correct option is B, Red dwarf stars.

Explanation:

Red stars are the coolest and most abundant kind of stars present in the milky way. They are also very small and cannot be seen by the naked eye of a human. As the red stars are about 50% smaller than the sun, their surface remains cooler than the other stars. As a result of this cool surface, the red stars acquire the shiny red colour. Hence, the description of red stars matches with the hints given in the question.