What is the definition of "surreptitious"?

The term "surreptitious" refers specifically to something that is done in a secretive or stealthy manner, often because it would not be approved of or is not meant to be known publicly. This aligns perfectly with the definition provided in the correct choice. It emphasizes the element of secrecy and the idea that the action is concealed from view or knowledge, often due to the nature of what is being done being considered inappropriate or unacceptable. In contexts where one is trying to avoid detection or approval, "surreptitious" is the precise term to describe such behavior, highlighting the intention to keep something hidden.