C. Match the preceding qualifier zero or one time. In regular expressions, the "?" symbol is used as a quantifier to indicate that the preceding element or group should be matched zero or one times. It makes the preceding element or group optional, meaning it can occur either once or not at all. Here are a few examples to illustrate the usage of the "?" symbol: Match "colour" or "color": colou?r This pattern matches both "colour" and "color." The "?" makes the "u" optional, allowing for both spellings.

Correct question is "What does the ? symbol within regular expressions represent?"

What symbol?