(A)-(C) The fitting chi2 are plotted against the ensemble size for complete sfRNAs of DENV2 (A), ZIKV (B) and WNV (C), suggesting optimized minimal structural ensembles with 3, 3 ,3 conformers, respectively. The respective insets show the distribution of the minimal ensembles and the initial pools of 10000 random conformers as a function of Rg. 