Comparison between the ESPRESSO transmission spectrum and the retrieval analyses under different model assumptions. Panel a considers a planetary atmosphere composed of only H, H₂, and He. Additional gas absorbers are added in Panels b–f. Panel g assumes only the stellar contamination to account for any transit depth variation, while Panel h includes both planetary atmosphere and stellar contamination. Of these model assumptions, an atmosphere containing H₂O and NH₃ gives the highest Bayesian evidence (Panel f).