Explanation:

- Option 1: Proposal + Acceptance = Promise

When one party makes an offer and the other accepts, it forms a promise.

- Option 2: Promise + Consideration = Agreement

A promise turns into an agreement when both parties exchange something of value.

- Option 3: Agreement + Enforceability = Contract

For an agreement to become a contract, it must be legally enforceable.

- Option 4: All the above

Each statement builds correctly in the process of forming a contract.