If the sales price is adjusted based upon a survey, either party may terminate the contract if the sales price varies by more than:

In Texas real estate transactions, an adjustment to the sales price based on a survey can lead to contract termination under specific conditions. The correct answer specifies that either party may terminate the contract if the sales price varies by more than 5%. This threshold is a standard provision designed to provide a clear boundary to protect both the buyer and the seller from significant discrepancies that could arise due to a property's survey results.

If the variance surpasses this predetermined percentage, it acts as a safeguard, allowing parties the option to withdraw from the agreement without consequence. The use of a percentage rather than a fixed dollar amount (as suggested in some other options) allows for flexibility across different price points and property values, ensuring that both parties are treated equitably regardless of the actual sales price. This policy helps to mitigate potential disputes and fosters a clearer understanding of the terms of the agreement.

In contrast, the other options refer to specific amounts or conditions outlined within various sections of the contract, but they do not represent the standard guideline used in the context of price adjustment based on survey outcomes. Hence, relying on a percentage is a more universally applicable and practical approach in this scenario.