* Inquired means to ask a question or to seek information.
* Replied means to answer a question or to give a response.
Here's how they relate:
* Someone inquires by asking a question.
* Someone replies by providing an answer.
Therefore, "replied" is more like the response to an inquiry.
Some possible opposites of "inquired" could be:
* Answered
* Told
* Explained
* Stated