Which of the following is NOT a source of rental income data?

The correct response highlights that insurance agents typically do not serve as a direct source of rental income data. Instead, their primary function revolves around providing coverage for properties, handling claims, and managing risk for clients, rather than collecting or analyzing rental income information.

In contrast, commercial property managers oversee the rental operations of properties, providing vital insights into rental rates and occupancy levels. Real estate brokers and salespeople are deeply involved in the market dynamics of properties, offering relevant information regarding rental trends and income potentials derived from their dealings. Public records, on the other hand, often contain official data related to property rentals, including lease agreements and tax assessments, which can help in understanding rental income trends.

Thus, while each of the other options plays a critical role in the real estate market, insurance agents typically do not engage with rental income data in the same way.