  We use updated gas mass fraction measurements of 44 massive dynamically
relaxed galaxy clusters collated in arXiv:2111.09343 to distinguish between the
standard $\Lambda$CDM model and $R_h=ct$ universe. For this purpose, we use
Bayesian model selection to compare the efficacy of both these cosmological
models given the data. The gas mass fraction is modeled using both
cosmology-dependent terms and also astrophysical parameters, which account for
the variation with cluster mass and redshift. We used two different prior
choices for some of the astrophysical parameters. We find a Bayes factors of 50
and 5 for $\Lambda$CDM as compared to $R_h=ct$ for these two prior choices.
This implies that $\Lambda$CDM is favored compared to $R_h=ct$ with
significance ranging from substantial to very strong.
