Which of the following malware types may require user interaction, does not hide itself, and is commonly identified by marketing pop-ups based on browsing habits?

A botnet is a network of covertly compromised machines controlled by a command-and-control server and does not display marketing pop-ups.

A rootkit is specifically engineered to hide deeply within the OS, which directly contradicts the 'does not hide itself' characteristic.

Adware generates revenue by presenting targeted advertisements based on the user's browsing habits, frequently through pop-up windows. Unlike rootkits or viruses, adware does not attempt to hide its presence because its goal is to display visible ads; it is also commonly distributed as part of free software installers that users willingly run, distinguishing it from purely silent malware.

A virus self-replicates by infecting other files and does not characteristically display browsing-habit-based marketing content.