Explanation:

- Contracts with an alien friend (meaning a person who is not a citizen of the country) are generally valid, but this is subject to certain government restrictions regarding trade, security, or public policy.

- If the contract concerns a subject restricted by law (such as property ownership or sensitive technology transfer), it may be unenforceable or void to that extent.

- Void contracts are those that are not recognized by law from the beginning, while unenforceable contracts are valid but cannot be enforced in a court due to some technical defect.

- Invalid is not a technical legal term but commonly means the same as void.

Correct Answer: Option 3 - Valid (subject to restrictions)