Three-month and six-month Treasury bills are auctioned by the Federal Reserve Board:

The correct answer is that three-month and six-month Treasury bills are auctioned weekly. This regular auction schedule allows the Treasury to efficiently manage its short-term borrowing needs and provides investors with consistent opportunities to purchase these securities.

Auctioning these Treasury bills weekly helps maintain liquidity in the market, allowing participants to react to changing economic conditions and funding requirements. The regularity of the schedule attracts a broad range of investors, including individual buyers, institutional investors, and foreign governments, all of whom may have varying investment time horizons and liquidity needs.

The other choices do not reflect the actual auction frequency for these Treasury securities: daily would not provide adequate time for preparation and allocation, monthly would be too infrequent for the government's short-term financing, and annually wouldn't meet the immediate funding needs that these short-term bills are designed to address.