In a situation where an arrest is needed for a public offense, what must a private person observe?

In the context of making a citizen's arrest, the key requirement is that the offense must be committed in the observer's presence. This principle ensures that the private individual has firsthand knowledge of the crime, making the arrest legally justifiable. Observing the crime ensures that the arresting individual is not acting on hearsay or assumptions, which could lead to wrongful arrests or misuse of power.

The necessity of witnessing the offense serves to uphold the standards of justice and legality, allowing only those with direct evidence of wrongdoing to intervene. This requirement protects individuals from potential legal repercussions that can arise from making unfounded accusations or arrests based on speculative circumstances.

In contrast, the other options do not apply universally to citizen's arrests. While certain crimes may be felonies, the definition does not restrict non-law enforcement personnel to only arrest based on felonies. A suspect's admission of guilt can strengthen a case but is not a legal requirement for making an arrest. Lastly, the availability of law enforcement is not a determining factor; citizens can act independently regardless of police presence as long as the circumstances meet the required legal criteria. Therefore, the correct answer emphasizes the need for direct observation of the offense committed.