Although partially destroyed, the archaeologists were able to infer

Hi arirux92, Please have a look at my view below:

If there is one pronoun and one possible noun antecedent, it does not matter whether the noun antecedent and the pronoun are both subjects, both objects or one subject/ one object. In such case, a pronoun subject of one clause may refer to a noun object of another clause. On the other hand, a pronoun object of one clause may refer to a noun subject of another clause.

However ambiguity may arise when there are 2 antecedents and 1 pronoun. Nonetheless, if there is one pronoun subject in one clause and one possible noun antecedent in subject and one possible noun antecedent in object in another clause, the subject pronoun would unambiguously refer to the subject noun by virtue of parallelism. In your example the pronoun it unambiguously refers to bull - this usage is accepted in GMAT.

In the question above, ambiguity does not arise at all (between archaeologists and inscription), since there is one pronoun it and only one possible (singular) antecedent inscription. It is not wrong that the pronoun is subject in one clause and the antecedent is in predicate of another.

Please note that ambiguity may still arise between crypt and inscription. However because of the relative distances of the nouns inscription and crypt from the pronoun it - moreover crypt is in an altogether separate subordinate clause starting with that - the pronoun it still refers, although slightly ambiguously to inscription. This usage is also acceptable and although slightly ambiguous, not sufficient to eliminate an answer.