What type of intrusion involves observing someone without their knowledge?

The correct answer is visual intrusion, which specifically refers to the act of observing someone without their knowledge or consent. Visual intrusion encompasses various forms of observation, such as peeping, surveillance, or using technology to watch someone secretly. This type of intrusion focuses on the unauthorized viewing of an individual, violating their privacy rights.

In contrast, physical intrusion pertains to an actual breach of someone's personal space or property, while auditory intrusion involves listening to someone without their knowledge, such as eavesdropping on conversations. Psychological intrusion typically refers to more abstract forms of invasion, such as manipulating someone's thoughts or emotions. Therefore, visual intrusion is the most accurate description of the act of observing someone without their awareness.