What kind of contract describes the property, states the amount of commission to be paid, states an expiration date, and is signed by the seller?

An offer to purchase is a proposal made by a buyer to a seller to buy a property at a specified price. While it may contain important terms such as the purchase price and conditions, it does not include a commission structure or an expiration date relevant to the agent's representation. Its primary focus is on the buyer's intent to purchase rather than the seller's responsibilities.

A contract to sell is a legal agreement between a buyer and seller that outlines the terms of the sale, including price and contingencies. However, it is typically executed after a listing contract and does not detail the commission to be paid to the listing agent or specify an expiration date for the seller's agreement with the agent.

An option agreement provides a buyer the right, but not the obligation, to purchase a property at a specified price within a certain time frame. This type of contract does not pertain to the commission structure for a real estate agent or the seller's obligations, focusing instead on the buyer's rights concerning the property.