Final answer:
Federal judges are nominated by the president, confirmed by the U.S. Senate, and appointed for an indefinite period, providing they maintain 'good behavior'.
Step-by-step explanation:
The correct answer is d. All of the answers are correct.
Federal judges are nominated by the president (a), confirmed by the U.S. Senate (b), and appointed for an indefinite period, providing they maintain 'good behavior' (c). This means that all of the given options in the question are correct.
Judges in the U.S. serve lifetime terms of office, which allows them to be free from undue political influence and pressure to decide a case according to the desires of the President or Congress. This helps ensure the independence of the judiciary.