Which statements are true regarding T-bills?

The statement that T-bills trade at a discount to par is indeed accurate. Treasury bills (T-bills) are short-term government securities that are issued at a price lower than their face value, or par value. Upon maturity, the holder receives the full par value, which creates the yield for the investor. This discount pricing structure is a key characteristic of how T-bills function as investment vehicles, providing a low-risk option for those looking to invest in U.S. government debt.

In addition, it's important to note that T-bills have a maximum maturity of one year or less, and they are indeed direct obligations of the U.S. government. However, they are not callable, meaning they cannot be redeemed before their maturity date by the issuer. Understanding these specifics is essential for grasping how T-bills operate within the broader context of fixed-income securities.