Dividing the colors

In the above, [A] shows the three primary colors of light, and [B] is some section of helium line spectrum, where we can see a yellow line. Which of the following statements is correct?

a) If we see the yellow color of [A] with a spectrometer, we can see one line.

b) If we see the yellow color of [B], then only M-cone cell, which responds the most to light of medium-wavelength, peaking at a green color, responds to it.

c) If we use the three primary colors of light, we can make all colors of line spectrum in [B].