B: The Federal Government needs to respond quickly.
Congress needs to go through a long and careful process to get things done, not to mention them needing to have the majority of congress agree.
The president/executive branch of the government is made up of much less people, as well as the president himself being commander and chief of the military.
Time is very important during a national emergency, and the president can get things done quickly.
Hope this helps.
The branches work against eachother when it comes to laws. The legislative branch makes laws, but the President can veto those laws with a Presidential Veto. The legislative branch makes laws, but the judicial branch can declare those laws unconstitutional.
The blending of greek and roman philosophies with christian ideas