In America, judicial independence is achieved mainly through which of the following means?

A、Thepresidentnominatesthefederaljudgeswhilethesenateapprovesthenominees.;
B、Federalcourtscandeclarepresidentialactsunconstitutional.;
C、Lifetenureforfederaljudges.;
D、Protectedsalariesforfederaljudges.