Comparison between ice abundances with respect to H₂O ice. The left panel shows the ice abundances in IRAS 2A and IRAS 23385. The solid line indicates the 1:1 abundance relation, whereas the dashed and dot-dashed lines indicate the enhancement and diminution of IRAS 23385 abundance by a factor of 3. The right panel compares the ice abundances between IRAS 2A and the comet 67P/G-C from Rubin et al. (2019). The solid line indicates the same as in the left panel. The dot-dashed and dashed lines indicate a cometary abundance lower by a factor of 10 and 100, respectively.