Which agency is primarily concerned with investigations related to security and criminal activities?

The correct agency primarily concerned with investigations related to security and criminal activities is HSI, which stands for Homeland Security Investigations. HSI plays a crucial role within the Department of Homeland Security (DHS) and is responsible for enforcing immigration and customs laws. This includes investigating various criminal activities such as human trafficking, drug smuggling, and financial crimes that pose a threat to national security and public safety.

HSI's investigative authority allows it to tackle a wide range of issues at both domestic and international levels, making it an essential agency in maintaining security and addressing criminal conduct that can undermine safety in the U.S. By focusing on both immigration enforcement and broader criminal investigations, HSI is positioned effectively to respond to threats and enforce laws designed to protect the homeland.

In contrast, the other agencies mentioned have specific roles that may not directly focus on criminal investigations. For example, HQFDNS relates more to the operations of the Department of Homeland Security's various programs. HIFCA and HCT are not recognized agencies specifically tasked with the broad scope of criminal investigations related to security matters. Thus, HSI stands out as the primary authority in this context.