A student using a spectrometer sees three different first-order colors (A, B, & C) at the following angles: θₐ₁=8.6°, θᵦ₁=11°, & θc₁=13.1°. The grating has...
a) 1000 lines/cm
b) 1200 lines/cm
c) 800 lines/cm
d) 1500 lines/cm