Final answer:
The parol evidence rule permits the introduction of evidence of the parties' prior negotiations, prior agreements, and contemporaneous oral agreements at trial (option 4), although such evidence is typically admitted only to clarify ambiguities, or in cases of fraud, duress, or mistake.
Step-by-step explanation:
The parol evidence rule prevents the introduction of evidence of prior or contemporaneous negotiations and agreements that contradict, modify, or vary the contractual terms of a written contract if that contract is intended to be a complete and final expression of the parties' agreement. Therefore, of the provided options, the correct answer is (4): All of the above. The parol evidence rule allows for the introduction at trial of evidence regarding the parties' prior negotiations, prior agreements, and contemporaneous oral agreements, but typically only to clarify ambiguities in the written contract, to show that the contract was void or voidable, for purposes of interpreting the contract's terms, or to prove issues such as fraud, duress, or mistake. It is important to note that while the parol evidence rule is a general principle in contract law, its application can vary based on the jurisdiction and the specific circumstances of a case.