If a constructor 'Date' is declared explicit and has to be defined outside the class, which of the following is correct?

1. ADate::Date(int dd) { /* ... */ }
2. Bexplicit Date::Date(int dd) { /* ... */ }
3. CSuch a constructor cannot be defined
4. DA constructor always has to be defined inside the class

Pick an option to check yourself, or open the answer below.