Carbon-to-iron (left panel) and carbon-to-oxygen (right panel) abundance ratios as functions of [Fe/H] and [O/H], respectively, in the Galactic bulge. The solid lines show the predictions of the chemical evolution model for the bulge by Matteucci et al. (2019), including the same nucleosynthesis prescriptions as models MWG-05 (brown), MWG-06 (orange), and MWG-07 (yellow) of Romano et al. (2019). Data for microlensed bulge dwarfs from Johnson et al. (2008, filled circles) and Cohen et al. (2009, empty circles) are also shown. All abundance ratios were normalised to the solar photospheric abundances by Asplund et al. (2009).