Which explains why supreme court justices are given lifetime appointments?

I believe the answer is: They protect justices from political pressure.

If supreme court is replaced every time the president is changed, the chosen supreme court would most likely feel pressured to conform to the will of the political parties that help his/her election. To prevent this, the supreme court is appointed for lifetime.

the answer is a) james madison.

you aint got nothin on my lil weenies