Which of the following influenced the increased focused on national security

A. War on terror

B. war in Afghanistan

C. September 11 attacks

D. War in Iraq

C: Sep. 11 attacks

The increased focused on national security was due to C: September 11 attacks.

September 11 attacks were a series of four coordinated terrorist attacks by the Islamic terrorist group al-Qaeda against the United States.

As a result of this, several measures were taken to coordinate anti-terrorism efforts, such as the creation of the Department of Homeland Security and the increase of power of the Federal Government. This allowed the US Government to, for example, monitor communications and detain suspects in order to increase the effectiveness of prevention measures, among others.