Which document may be attached to a purchase contract?

The appraisal contingency notice is the correct answer because it serves a specific purpose in the context of a purchase contract. This notice allows buyers to set a condition that the property must appraise at or above a certain value for the transaction to proceed. It protects the buyer from overpaying for a property, ensuring that financing can be secured based on the property’s appraised value.

In real estate transactions, contingencies are vital as they outline certain conditions that must be met for the contract to be enforceable. Including an appraisal contingency notice in the purchase contract clearly specifies this condition, which is essential for the buyer's peace of mind and financial security.

In contrast, other options like the employment agreement, listing contract, and sales contract serve different functions and aren't typically attached directly to a purchase contract. An employment agreement relates to employment relationships, a listing contract is focused on the seller's agreement with their real estate agent, and although a sales contract might seem related, it typically refers to a broader transaction than the specific purchase contract being considered in this context.