A buyer and seller agreed upon a selling price for a property and both signed...

Comprehensive and Detailed Explanation (150–250 words):

An executory contract is one in which one or more terms remain to be performed. In this case, although the purchase agreement is signed, the buyer’s performance is contingent upon selling their home within 30 days. Until that contingency is satisfied, the contract remains executory.

A (executed contract): would mean all terms have been performed.

B (unilateral contract): involves only one party making a promise, e.g., an option. This is bilateral.

D (implied contract): arises by conduct, not by a written agreement.

Thus, the correct answer is C: executory contract.