Which pattern uses a numeric wildcard to denote a single unspecified digit?

Which pattern uses a numeric wildcard to denote a single unspecified digit?

• A. b[a-c]d
• B. [!ae]
• C. 123
• D. 1#3

Answer: (D)

A numeric wildcard is a symbol that stands for any single digit (0–9) in a pattern. In these options, the one that uses such a wildcard is the pattern with a # between two fixed digits. The pattern 1#3 means the first character must be '1', the middle character can be any digit, and the last character must be '3'. So it could match strings like 103, 123, 193, and so on. The other patterns use different mechanisms: b[a-c]d picks a single character from the range a to c; [!ae] matches any single character except a or e; and 123 is just a literal sequence with no wildcard.

A numeric wildcard is a symbol that stands for any single digit (0–9) in a pattern. In these options, the one that uses such a wildcard is the pattern with a # between two fixed digits. The pattern 1#3 means the first character must be '1', the middle character can be any digit, and the last character must be '3'. So it could match strings like 103, 123, 193, and so on. The other patterns use different mechanisms: b[a-c]d picks a single character from the range a to c; [!ae] matches any single character except a or e; and 123 is just a literal sequence with no wildcard.