Which explains why supreme court justices are given lifetime appointments?

they give justices original jurisdiction.
they protect justices from political pressure.
they connect justices to appellate courts.
they provide justices with unlimited power.

They protect justices from political pressure.

Explanation:  

The justices' main role is to evaluate laws and decide on cases between two or more parties according to the law. They hold hearings, discuss the cases and come to a conclusion. And in order to impartially carry this task, they are given lifetime appointments so that they do not feel pressured to gain people's vote when running for re-election and the pressure to determine cases based on what people would like. Instead, they are expected to decide cases objectively, according to the law.

it all depends on how long the hours are. i think they wouldn't approve of it. in my opinion.