Which of the following is not typically recognized as a valid type of contract?

The correct choice focuses on the terminology used in contract law. Implied by law contracts, also known as "quasi-contracts," are not recognized as traditional contracts in the same sense as the other options. Instead of being formed through the mutual assent of parties, these arise from a legal obligation created by the court to prevent unjust enrichment. Thus, while they share some characteristics with real contracts, they do not typically involve an agreement that has been expressly stated or implicitly understood between parties to create an enforceable obligation.

In contrast, expressed contracts are explicitly stated in words, either spoken or written, and reflect the mutual intentions of the parties involved. Implied by fact contracts are inferred from the actions or conduct of the parties, indicating that they intended to create an agreement. Bilateral contracts involve mutual promises made by both parties, with each party committing to fulfill their respective obligations.

Understanding the distinctions among these types of contracts is crucial for recognizing which contracts hold enforceable agreements versus those that the law imposes to avoid inequitable outcomes.