Which of the following best describes a mutual fund?

A mutual fund is best described as an open-ended investment company that pools money from multiple investors to invest in a diversified group of securities, which may include stocks, bonds, or other financial instruments. This structure allows individual investors to gain exposure to a broad range of assets, increasing diversification and reducing individual risk associated with investing in single securities.

The open-ended nature means that the mutual fund can continuously accept new investment from clients and can issue more shares as needed, rather than being limited to a fixed number of shares like a closed-end fund. The professional management team of the mutual fund actively makes decisions about the fund's investments, aiming to meet specific investment objectives, which can range from growth, income, or a combination of both.

In contrast, a company offering fixed interest rates to investors does not reflect the diverse and actively managed nature of mutual funds. Similarly, a government entity managing public investments does not represent the private sector framework of mutual funds which cater directly to individual investors. Lastly, a firm that specializes only in corporate bonds is too narrowly focused and does not capture the broader scope of a mutual fund, which encompasses various types of securities and investment strategies.