Line intensity ratios of c-C₃H₂ transitions for the VeLLO, and the sample of Murillo et al. (2018) that consists of single protostars, close binary systems, and wide binaries. Close binaries in Murillo et al. (2018) are separated by < 2″, the wide binaries in this work have separations in the range of 7–46″. The ratios are plotted against the bolometric luminosity, L_bol in the upper panel, and against the envelope mass, M_env in the lower panel.