Explanation:

- Simple Imprisonment: A type of imprisonment where the convict is not required to perform hard labor.

- Rigorous Imprisonment: Involves compulsory hard labor while serving the sentence.

- Simple or rigorous imprisonment: The court has discretion to impose either simple or rigorous imprisonment based on circumstances.

- Solitary Confinement: Imprisonment where the convict is kept isolated from other inmates.

In case of default in payment of a fine, the imprisonment is typically simple. This means the person will serve time without hard labor, making Option 1 - Simple the correct answer.

Answer: Option 1 - Simple