What are the extended regular expression characters?

• A. ( ) { } | ? +
• B. ^ $ . * [ ]
• C. Backslashes only
• D. Digits

Answer: (A)

Extended regular expressions add metacharacters that let you build more powerful patterns with grouping and repetition. The set includes parentheses for grouping subexpressions, braces for quantifiers like {m,n}, the vertical bar for alternation (choosing between options), and the question mark and plus as additional quantifiers (zero-or-one and one-or-more). Together, these characters expand what you can express beyond the basics, allowing patterns like (cat|dog)+ or a{2,4}. The other symbols listed are anchors, character-class delimiters, or escape tools, not the extended set themselves, and digits aren’t metacharacters.