Twenty-four correctly written as a Roman numeral is

A. XXIIII: While this form was used in ancient times, it is now considered incorrect by modern Roman numeral standards. Roman numerals should follow subtractive notation, where 4 is written as IV, not IIII. B. XXIV: This is the correct modern Roman numeral for 24. It combines 20 (XX) and 4 (IV) using the proper subtractive rule for the numeral 4. C. Xxiiii: Roman numerals must be written in uppercase to be considered correct. This option also uses an outdated form (IIII for 4) and mixes cases. D. xixv: This is not a valid Roman numeral. It incorrectly places symbols and uses lowercase letters, violating both formatting and value rules.