Answer: C) out of the ordinary.
Explanation: The connotation of a word is the meaning given by the context or even by the readers (or listeners) based on their emotions or personal experiences. In the given excerpt from "The Count of Monte Cristo" the connotation of the word "uncommon" is the corresponding to option C: out of the ordinary, because Dante was hearing noises that he hadn't heard before, so he thought that something out of the ordinary was happening.