Question

what is the task of the united states department of homeland security?
to attack paramilitary terrorist groups
to aid in the prevention of terrorism abroad
to maintain the safety of all us citizens
to ensure the security of americans in other countries

Explanation:

The U.S. Department of Homeland Security's core domestic mandate is focused on protecting the safety of people within the U.S. The other options either involve offensive actions (not its primary task) or focus on international/abroad efforts, which fall outside its domestic scope.

Answer:

to maintain the safety of all US citizens