If the grammatical structure that is italicized is <em>although her personality had not changed at all, </em>then the correct answer is adverb clause. Adverb clauses function the same way simple adverbs do - they answer the questions such as why, where, when, how, etc.
Answer:
The one you selected is correct.
(Education is the best path to freedom because once a person has been educated, nothing can take that from them.)