As the interest rate on mortgage loans is decreasing, consumers are waiting to see how low the interest rate will be. Therefore, the number of new homes sold in January has dropped sharply. At the same time that sales have fallen sharply, the average price of new homes sold has surged. Which of the following, if true, best explains the surge in the average price of a new house:. ['Sales of higher-priced houses are not affected by the decline in sales, as their buyers are less limited by the total amount paid.', 'Labor agreement between builders and building unions expires next January.', 'The price of new homes has been rising slowly over the past three years, and the severity of the housing shortage has increased.', 'More homeowners sold their mid-priced homes again in January than in the previous three months.']