Top panel: bolometric luminosity vs. period obtained from the SED fitting of the C stars selected in this work: C stars in the SMC are indicated with red dots, and C stars in the LMC are plotted with blue triangles. For comparison, we overplot the population of C stars in the LMC for which the period has been determined from Riebel et al. (2012), which have been fitted by Nanni et al. (2019). To avoid superposition in the plot, M_bol has been changed by a random number between −0.25 and +0.25 mag. The sources for which the period has been flagged with a superscript “a” or “b” in Table C.2 are indicated with a cross. Middle and bottom panels: relations between MLR vs. the bolometric luminosity and MLR vs. period, respectively.