Julio emailed a contract to his vendor’s supply chain manager. Even though Julio sent the contract, the contract is not valid until the supply chain manager receives and executes the contract. What key principle about contracts does this scenario describe?

This scenario describes the key principle of contract formation, specifically the requirement of acceptance. The contract sent by Julio is not considered valid until the supply chain manager (the offeree) receives the contract and executes it, indicating their acceptance of its terms.