Which of the following is an appropriate step to defend against identity theft?

Focusing on the importance of closing tampered or fraudulently established accounts is crucial in defending against identity theft. When an individual becomes a victim of identity theft, it's likely that unauthorized individuals have gained access to their financial accounts, which can lead to significant losses. By closing these accounts, the victim can prevent further unauthorized transactions and limit their liability.

This step not only halts the immediate risk but also serves as a critical measure in protecting one's credit score and overall financial health. It's essential to act swiftly when fraudulent activity is suspected, as delays can result in complications, such as accumulating debt or ongoing fraud on their accounts.

Taking such proactive measures ensures that the victim has more control over their financial situation and can begin to restore their identity. Thus, closing tampered or fraudulent accounts is a vital action in mitigating the consequences of identity theft, making it the appropriate response in this scenario.