Final answer:
The element of a written agreement that can be enforceable under law is a contract. It must contain certain essential elements, including an offer, acceptance, consideration, and an intention to create legal relations.
Step-by-step explanation:
The element of a written agreement that can be enforceable under law is a contract. A contract is a legally binding agreement between two or more parties that creates rights and obligations for those involved. It must contain certain essential elements, including an offer, acceptance, consideration, and an intention to create legal relations.
While a letter of intent (a) and a memorandum of understanding (b) may outline the terms of a potential agreement, they are not typically enforceable as contracts. An offer (d) is a component of a contract, but it does not encompass all the necessary elements on its own.