Same as Fig. 10, this time displaying the percentage of stars which are binary against number of standard deviations of [C/Fe] abundance ratio from the mean for stars of the same population and similar [Fe/H]. The panels show the early high α, low α populations and the late high α population. The dotted lines show mean binary percentage across each entire sub-population. Error bars are based on binomial distribution of sub-population with uniform binarity independent of [C/Fe] variation. A similar trend in binarity is observed, ruling out the possibility that the trend against [C/O] is caused by O-poor stars.