Which one of the following is a correct definition of an Ibbotson and Sinquefield investment category as used to report historical returns in your textbook? U.S. Treasury bills: 1-year debt securities issued by the U.S. Department of the Treasury Small-company stocks: Stocks of the smallest 20 percent of the firms listed on the NYSE Large-company stocks: Stocks of the largest 10 percent of the firms listed on the NYSE Long-term U.S. government bonds: Bonds issued by the U.S. government with a 30-year maturity Long-term corporate bonds: Average quality bonds issued by U.S. firms with maturities of 15 to 20 years