Sally enters into a written contract with Roberta. Under the terms of the contract, Roberta promises to sell and Sally promises to buy a specific piece of land for $7,000. There is adequate consideration, the contract is legal, and both parties have contractual capacity. The contract is fully performed by both parties on January 1. Which of the following best describes this contract as of January 2?

		Unilateral, express, executory, valid.
		Bilateral, express, executed, valid.
		Unilateral, express, executed, valid.
		Unilateral, implied, executory, valid.