Recognizing key facts about the opposite of the opposite of a number, which of the following statements is correct?

A. The opposite of the opposite of a negative number is zero.
B. The opposite of the opposite of a negative number can be either positive or negative.
C. The opposite of the opposite of a negative number is a positive number.
D. The opposite of the opposite of a negative number is a negative number.

C. The opposite of the opposite of a negative number is a positive number.

The correct statement is D. The opposite of the opposite of a negative number is a negative number.