The correct answer is C. sharply.
The word “sharply” means in a sudden and forceful way. It is the most appropriate word to describe the tone of voice in which someone would say “Mind your own business” if they were trying to be assertive and stop someone from interfering in their affairs.
The other options are not as appropriate. The word “meekly” means in a timid and submissive way. This would not be the tone of voice someone would use if they were trying to be assertive. The word “heavily” means in a slow and deliberate way. This would not be the tone of voice someone would use if they were trying to be forceful. The word “clumsily” means in a awkward and ungainly way. This would not be the tone of voice someone would use if they were trying to be assertive.