The correct answer is C, Semiannually. U.S. Treasury bonds, along with Treasury notes, pay interest twice a year, which is referred to as semiannual payments.

Step-by-step, Treasury securities are debt obligations issued by the U.S. government. For Treasury bonds (long-term maturities of more than 10 years), the stated coupon rate determines the annual interest amount. However, this annual interest is divided into two equal payments, paid every six months to bondholders.

For example, if a Treasury bond has a $1,000 par value and a 6% coupon rate, it pays $60 annually. Instead of paying $60 once per year, the investor receives $30 every six months.

Choice A (monthly) and Choice B (quarterly) are incorrect because Treasury securities do not pay interest that frequently. Choice D (annually) is incorrect because, although the rate is quoted annually, the actual payments are split into two installments.

It is important to distinguish that Treasury bills (T-bills) do not pay periodic interest at all—they are issued at a discount and mature at par. In contrast, Treasury notes and bonds both pay semiannual interest, making Answer C correct.