C31: A diffraction grating is illuminated with yellow light at normal incidence. The pattern seen on a screen behind the grating consists of three yellow spots, one at zero degrees (straight through) and one each at ±45°. You now add red light of equal intensity, coming in the same direction as the yellow light. The new pattern consists of

1. red spots at 0° and ±45°.

2. yellow spots at 0° and ±45°.

3. orange spots at 0° and ±45°.

4. an orange spot at 0°, yellow spots at ±45°, and red spots slightly farther out.

5. an orange spot at 0°, yellow spots at ±45°, and red spots slightly closer in.