The correct option is B valid
Mistake of law can result in defeat of free consent as required for a valid contract. Mistake of law can be of Indian law or foreign law. Section 21 of the Indian Contract Act, 1872 states that a contract is not voidable if it has been induced by a mistake of law in force in India at the time of entering into the contract. But if it is a mistake of law not in force in India or foreign law, it is to be treated in the manner of mistake of fact. This is based on the maxim ignorantia juris neminem excusat or ignorance of law is no excuse.