The independence of the judicial branch is ensured by the a. manner in which federal judges are chosen. b. terms federal judges serve. c. salaries of federal judges. d. all of the above.

The correct option is D.
The judicial branch of a nation is made up of the system of courts that exist in that country. Members of the judicial branch are usually appointed by the president and confirmed by the senate. It is the responsibility of the judicial branch to interpret laws. The independence of the judicial branch depend on factors such as the number of terms federal judges can serve, salaries attached to the position, manner of appointment of the federal judges, etc. 

South carolina was so angry about the election of lincoln that they seceded from the union on december 20, 1860. they attacked fort sumter later, on april 12, 1861.

The answer should be d.