Explanation:

- Alien Enemies: They are citizens of a country that is at war with the home country. Laws often restrict their ability to engage in contracts for security reasons.

- Insolvents: Once declared insolvent, a person’s ability to manage their financial affairs is legally restricted. They cannot enter into contracts involving personal assets.

- Convicts: People serving a prison sentence may have their contractual rights limited, as they lack the freedom to manage their own affairs.

- Option 4: All of the above: This option is correct because each of the above categories includes individuals who may be disqualified from contracting due to legal restrictions.

Correct Answer: Option 4 - All of the above