Which of the following regular expressions denotes a language comprising all possible strings of even length over the alphabet ( 0 , 1 ) ?

• A. (0 | (0 | 1)*
• B. (0 | 1) *
• C. (0 | 1 ) (0 | 1)(0 | 1 ) *
• D. (00 | 01 | 1 | 10 )*