Final answer:
A bill of sale is required at the settlement to transfer ownership of the tractors.
Step-by-step explanation:
To transfer ownership of the tractors included in the sale of the farm, a bill of sale is required at the settlement. A bill of sale is a legal document that records the transfer of ownership of personal property, such as vehicles, from one party to another. It includes details such as the date of the sale, the parties involved, a description of the tractors, and the purchase price.