The correct answer is: B. investment banks.
Investment banks are financial institutions that assist individuals, corporations and governments in raising capital by underwriting and acting as the intermediary between an issuer of securities and the investing public. They also provide advice on mergers and acquisitions, restructurings, and other financial matters.
Commercial banks are financial institutions that provide a variety of financial services, including checking and savings accounts, loans, and investment products. They are regulated by the Federal Reserve System and are required to hold a certain amount of capital in reserve.
Savings banks are similar to commercial banks, but they are typically smaller and have a more limited range of services. They are also regulated by the Federal Reserve System, but they are not required to hold as much capital in reserve.
Credit unions are non-profit financial institutions that are owned by their members. They offer a variety of financial services, including checking and savings accounts, loans, and investment products. They are regulated by the National Credit Union Administration.
In conclusion, investment banks are the firms that specialize in helping companies raise capital by selling securities.