Plot of PC ₁ vs. PC ₂ for EROs in our sample. (a) EROs are colored with , (OGs) are red, DGs are blue. (b) [3.6] − [8.0] < −0.95, [3.6] − [8.0]>0.0, and −0.95 < [3.6] − [8.0] < 0.0 are colored as red, green, and blue, respectively. (c) log  G > − 0.35 (OGs) are plotted as red and DGs as blue. (d) EROs are colored with the best-separated line from panel (a) and panel (c).