Which of the following regulations in the Securities Exchange Act of 1934 governs the extension of credit by banks to their customers for the purpose of carrying margin securities?

The regulation that governs the extension of credit by banks to their customers for the purpose of carrying margin securities is Regulation U. This regulation primarily addresses how financial institutions can extend credit and set guidelines to ensure that this is done responsibly, particularly in relation to the purchasing of securities on margin. It establishes the necessary requirements for banks and other lenders, including the limits on the amount of credit that can be extended based on the value of the securities being purchased.

Regulation U is part of the broader framework of the Securities Exchange Act of 1934, which was established to regulate the securities industry and protect investors. This regulation ensures that lending practices related to margin accounts align with financial stability and sound risk management principles. It is crucial for maintaining transparency and reducing the systemic risk associated with highly leveraged trading.

In contrast, the other regulations mentioned are not specifically aimed at the extension of credit for margin securities. Each of those regulations focuses on different aspects of securities trading and investor protection, which may include trading practices or reporting requirements but do not directly relate to the management of margin lending by banks.