Distribution of M/D obtained by fitting the 2017 (blue) and 2018 (red) data with the fiducial models shown in Table 3. These distributions are generated from the top 10% best-fitting snapshots by χ². The results for models prepared by the KHARMA, H-AMR, and BHACpipelines are shown separately, together with the result for all the models combined. The distribution when combining both the 2017 and 2018 result by the multi-epoch scoring algorithm is shown as the black profile. The vertical dashed black line and shaded gray region mark the ranges of M/D = 3.8 ± 0.4 μas reported in Event Horizon Telescope Collaboration (2019a).