Which of the following describes a "security"?

The definition of a "security" encompasses all financial instruments that can be traded, which distinctly includes stocks, bonds, and other similar financial assets. This aligns with the concept of a security as something that represents an investment in a common enterprise with an expectation of profits primarily from the efforts of others.

While stocks and bonds are the most commonly referenced types of securities in this context, the key characteristic is their tradability and the fact that they offer the potential for returns based on the performance of an enterprise or underlying asset. This is fundamental to the operation of financial markets, where such assets can be bought and sold.

The other options describe scenarios or categories that do not accurately encapsulate the broad and specific definition of a security as recognized in financial regulatory frameworks. An investment vehicle guaranteeing returns is misleading since securities inherently involve risk, and not all investments provide guaranteed outcomes. Additionally, an intangible asset that cannot be freely traded does not constitute a security since securities are by nature tradable. Lastly, a real estate investment trust (REIT) is a specific type of investment vehicle that can be classified as a security, but it does not represent the broader definition that includes all tradable financial assets.