Which agency plays a crucial role in overseeing personnel security investigations?

The Defense Counterintelligence and Security Agency (DCSA) is the correct choice because it is primarily responsible for conducting personnel security investigations for individuals seeking access to classified information or employment in national security positions. The DCSA was established to streamline and centralize the background investigation process, ensuring that all security clearances and related investigations adhere to federal standards. This agency plays an essential role in safeguarding national security by ensuring that personnel with access to sensitive information are reliable, trustworthy, and free from any potential security risks.

In contrast, the other agencies listed—like the Department of Justice, Central Intelligence Agency, and Federal Trade Commission—do not have a primary focus on personnel security investigations for national security clearances. The Department of Justice has various law enforcement functions, the CIA handles intelligence and espionage efforts, and the Federal Trade Commission focuses on consumer protection and competition. Therefore, while these agencies have critical roles within the government, they do not specialize in the oversight of personnel security investigations in the way that DCSA does.