Selected ¹²C/¹³C abundance ratios as a function of time in the variants of simulation S2 (S2, red; S2_C20, green; S2_3C, orange; S2_3C_alt, blue). The dashed black line in each panel indicates the elemental ¹²C/¹³C ratio (68), except for C₃ for which a ratio of 34 is used as our model does not distinguish between CC¹³C and ¹³CCC. The results of simulations S2 and S2_3C overlap almost perfectly.