Except as otherwise provided in subsection (b) of this section, in a real estate transaction involving a single-family dwelling, a real estate broker, an associate real estate broker, a real estate salesperson, or a lawyer acting as a real estate broker may not require a buyer, as a condition of settlement, to employ a particular: title insurance company; settlement company; escrow company; mortgage lender, or financial institution as defined in the Financial Institutions Article; or title lawyer. A seller may not be prohibited from offering owner financing as a condition of settlement.