Under what circumstances can an officer reach inside a person's clothing during a pat down?

The correct answer focuses on the standard for conducting a pat down, known as a frisk, which is rooted in the need for officer safety. When an officer performs a pat down as part of a stop-and-frisk procedure, they are allowed to reach inside a person's clothing only if the object they feel is reasonably believed to be a weapon. This aligns with the legal precedent set by the Supreme Court case Terry v. Ohio, which allows officers to ensure their safety by briefly searching for weapons when they have a reasonable suspicion that a person is armed and poses a threat.

The other options involve circumstances that do not justify reaching inside a person's clothing. Consent may allow for a more thorough search but does not apply in the context of a simple pat down where the goal is to identify weapons. Nervous behavior and belligerence can provide context to an officer's assessment of the situation but do not constitute a valid reason to breach the boundary of a pat down. Only the clear feeling of an object that could potentially be a weapon allows for that deeper search under the principles of reasonable suspicion.