Implied Contracts:
An implied contract is a contract that is formed based on the behavior and conduct of the parties involved, rather than being explicitly stated in writing or verbally. These contracts are inferred by the law to ensure fairness and justice in certain situations where it would be unjust for one party to benefit at the expense of the other. Implied contracts can be categorized into two types: implied in fact and quasi contracts.

Implied in Fact Contracts:
Implied in fact contracts are formed when the parties involved have a mutual understanding and agreement, even though it may not be explicitly expressed. The terms and conditions of these contracts can be inferred from the conduct and actions of the parties. For example, if a person visits a restaurant and orders food, an implied in fact contract is formed between the customer and the restaurant. The customer is obligated to pay for the meal, and the restaurant is obligated to provide the food.

Quasi Contracts:
Quasi contracts, also known as implied-in-law contracts, are not actual contracts but legal remedies imposed by the court to prevent unjust enrichment. These contracts are not based on the intentions or agreements of the parties involved but are imposed by law to prevent one party from unfairly benefiting at the expense of another. Quasi contracts are typically applied in situations where there is no existing contract between the parties but one party has received a benefit from the other party, and it would be unjust for that party to keep the benefit without compensating the other.

Example of a Quasi Contract:
For example, if a person mistakenly delivers a package to the wrong address, and the recipient keeps the package without notifying the sender, a quasi contract may be imposed. The recipient has received a benefit (the package) without any legal right to it, and it would be unjust for them to keep it without compensating the sender. In such a case, the law may imply a contract requiring the recipient to return the package or compensate the sender for its value.

Conclusion:
In conclusion, the correct answer is option 'C' - quasi contracts. Quasi contracts are the contracts implied by law to prevent unjust enrichment and are not based on the intentions or agreements of the parties involved. Implied in fact contracts, on the other hand, are formed based on the conduct and behavior of the parties, while contingent contracts involve conditions that need to be fulfilled for the contract to become enforceable.