That there was a fire. That a while ago fire was dramatic and popular.
Antecedent of a pronoun is a word that the pronoun refers to, or replaces. So, in this sentence, we are looking for the antecedent of the pronoun IT. The pronoun IT replaces the noun Chicago, which means that the word Chicago is the antecedent of the pronoun IT.
IT provides the best opportunity, meaning that Chicago does that.
The subject would be owner since the owner is male or female and is a person as well.