What type of investment is typically offered by a mutual fund?

A mutual fund is designed to pool money from multiple investors to invest in a diversified portfolio of securities, which can include stocks, bonds, and other financial instruments. This diversification helps to spread risk, as the fund is not reliant on the performance of a single investment. The professional management of the mutual fund aims to optimize returns for investors based on the fund's specific investment objectives.

In contrast, the other options represent different investment types that are not typically associated with mutual funds. Real estate investments focus on physical properties, fixed deposits are low-risk savings products not traded like mutual funds, and commodities trading involves direct investment in physical goods like gold or oil rather than a structured portfolio of securities. Hence, the diversified portfolio of securities is the defining characteristic of mutual funds, making it the correct choice.