[C/Fe] vs. [Fe/H] ratios for different models. Upper panel: [C/Fe] vs. [Fe/H] ratios as predicted by the one-infall model for different stellar yields and percentages of binaries (see legend). The thin gray dashed lines indicate the solar ratios. Lower panel: [C/Fe] vs. [Fe/H] ratios as predicted by the two-infall model for different stellar yields and compared with data from Nissen et al. (2020, white points) and APOGEE (Abdurro’uf etal. 2022).