Final answer:
The agreement between Farmer Smith and Joe to increase the price for drilling the well is a valid settlement of a liquidated debt. The correct answer is option a.
Step-by-step explanation:
The correct answer is option a. This is a valid settlement of a liquidated debt.
A liquidated debt refers to a debt for a fixed, certain, and agreed-upon amount. In this case, Joe and Smith had a contract for drilling a well for a price of $500. However, the unexpected hard bedrock presented a new circumstance that would substantially increase the time and cost of drilling. Therefore, by agreeing to pay Joe $2,000, Smith is settling the increased cost of drilling, which is a valid settlement of a liquidated debt.