Which sentence in the paragraph is the best topic sentence?

Interest rates dictate the amount a buyer can qualify for or if a buyer can qualify at all. Every time interest rates go up it eliminates buyers from the market. The lower the rate of interest on real estate loans the better it is for the market in general. Lower interest rates allow more people to buy and more people to purchase homes that are more luxurious. The downside to a low interest rate is that it has a tendency to make prices of homes elevated therefore, it creates more buyers.