Gaia (upper left), 2MASS (upper right), IRAC (bottom left), and MIPS (bottom right) CMDs of the final RSG sample in the SMC. Targets in the overlapping region (green lines) between AGBs and RSGs on the 2MASS CMD are removed (open black circles). Other general stellar populations, e.g., AGB, RGB, TRGB, and BSG stars, are marked on the Gaia and 2MASS CMDs, but not on IRAC and MIPS CMDs due to the overlap between different populations (see Fig. 12 of Yang et al. 2021a). Background targets (gray dots) are from Yang et al. (2019).