The correct answer is A. U.S. Treasury bills.
U.S. Treasury bills are short-term debt obligations issued by the U.S. government. They are considered to be one of the safest investments in the world, as the U.S. government has never defaulted on its debt. Treasury bills are issued in denominations of $100, and have maturities of 4, 13, and 26 weeks. They are sold at a discount to their face value, and pay interest at a rate that is determined by the auction process.
Commercial paper is a short-term unsecured promissory note issued by a company. It is typically used to finance short-term working capital needs, such as inventory or accounts receivable. Commercial paper is considered to be a riskier investment than Treasury bills, as it is not backed by the full faith and credit of the U.S. government.
A certificate of deposit (CD) is a time deposit account offered by banks and other financial institutions. CDs have a fixed interest rate and maturity date, and cannot be withdrawn before maturity without penalty. CDs are considered to be a safe investment, as they are insured by the Federal Deposit Insurance Corporation (FDIC) up to $250,000 per depositor.
A mutual fund is a professionally managed investment fund that pools money from many investors to purchase securities. Mutual funds are available in a variety of types, including stock funds, bond funds, and money market funds. Mutual funds are considered to be a riskier investment than Treasury bills, as they are subject to market risk.