Which scenario allows for the protection of third persons’ property through force or deadly force?

The choice indicating that the actor believes a theft is happening is the correct answer because, in many jurisdictions, the use of reasonable force to protect property is permissible if an individual has a genuine belief that a crime, such as theft, is occurring. This reflects the legal principle of defense of property, which allows a person to intervene to protect someone else’s possessions if they perceive an immediate threat.

In this context, 'reasonable force' can mean using necessary measures to prevent the theft, which could include non-lethal physical intervention or, in extreme circumstances and depending on local laws, even the use of deadly force if there is a significant belief that the threat to the property also poses a threat to a person’s life. The emphasis is on the perception and immediacy of the threat involved.

The other options would not justify the use of force. Having a personal relationship with the property owner, being related to them, or believing that the property is worthless do not inherently create a legal justification for using force. Instead, such criteria may complicate the situation further without providing a solid, justifiable context for intervening with force in defense of property.