The second option because it uses proper tense (past tense), the rest do not make sense it mixes the tenses (past, current, future).
A.
While the opinion of the author is used here (which is not necessarily fact), the fact that the author gives the year that the cages were built, and gives a description of them implies that these are both facts that provide evidence supporting the description of the Central City Zoo as being "small and outdated".
