Which of the following is true regarding a seller-financed mortgage?

A seller-financed mortgage, also known as owner financing, involves the seller acting as the lender for the buyer. In this scenario, the buyer does indeed have to report their Social Security Number (SSN) to the seller. This is important because the seller, as the lender, needs the SSN for tax reporting purposes. Seller financing typically requires the seller to report interest income received from the buyer to the IRS, and this necessitates having the buyer's SSN for accurate reporting on tax forms.

In addition, it's worth noting that the other options do not apply correctly to seller financing. Seller financing is available for both residential and commercial properties, not exclusively to commercial buyers. The seller can receive a variety of payments, including both principal and interest, rather than just principal payments. Lastly, the payment terms in a seller-financed mortgage are usually agreed upon directly between the buyer and seller, without the involvement of third-party lenders who would set terms for traditional mortgages.