A Student Looks Through a Transmission Grating at the Light

Multiple Choice

A student looks through a transmission grating at the light from a helium light source. He sees the red, yellow, and green light from the source superimposed on a meterstick. If the yellow lines are the ones indicated in the figure, then

A) 1 and 2 are green; 3 and 4 are red.
B) 1 and 4 are red; 2 and 3 are green.
C) 1 and 4 are green; 2 and 3 are red.
D) 1 and 3 are red; 2 and 4 are green.
E) 1 and 3 are green; 2 and 4 are red.