Explanation:

- The correct answer is: Option:1 - Irregular

- Irregular marriage: This is a marriage where the foundation is valid, but a required legal formality is missing. For example, missing witnesses or incomplete registration. It is not void, but needs correction.

- Void marriage: Completely invalid from the beginning, usually due to prohibited relationship or insanity. Cannot be made valid later.

- Valid marriage: All legal requirements and formalities are met. No issue.

- Invalid marriage: Not a standard legal term. Usually, the law uses "void" or "voidable."