Builders corporation files a suit against concrete company to enforce a written contract. if the court finds that the parties intended the contract to be the final statement of their agreement, parol evidence can be admitted to prove.

d. an orally agreed-on condition precedent.

Explanation:    

Contract law regulates the obligations established by agreement, whether express or implied, between private parties in the United States. The law of contracts varies from state to state; there is nationwide federal contract law in certain areas, such as contracts entered into pursuant to Federal Reclamation Law.  

The law governing transactions involving the sale of goods has become highly standardized nationwide through widespread adoption of the Uniform Commercial Code. There remains significant diversity in the interpretation of other kinds of contracts, depending upon the extent to which a given state has codified its common law of contracts or adopted portions of the Restatement (Second) of Contracts.