The correct answer is (c).
Residex is a house price index that measures the change in the value of residential property in the United Kingdom. It is published by the Nationwide Building Society and is based on the prices of a sample of properties sold each month.
Share prices are the prices at which shares in a company are bought and sold on a stock exchange. Mutual fund prices are the prices of shares in a mutual fund, which is a type of investment fund that pools money from many investors and invests it in a variety of assets. Land prices are the prices at which land is bought and sold.
Share prices, mutual fund prices, and land prices are all affected by a variety of factors, including economic conditions, interest rates, and investor sentiment. However, Residex is specifically designed to measure changes in the value of residential property, and is not affected by the same factors as share prices, mutual fund prices, or land prices.