What does the eighth amendment prohibit? lengthy trials search warrants cruel and unusual punishment impartial juries

The correct answer is " cruel and unusual punishment."

Amendment VIII - Bail, Cruel and Unusual Punishment

Excessive bail shall not be required, nor excessive fines imposed, nor cruel and unusual punishments inflicted.

The Cruel and Unusual Punishments Clause is the most important and also the most controversial part of the Eighth Amendment.  

It is a mystery, after all what does it mean for a punishment to be cruel and unusual?  And how can we measure a punishment’s cruelty?

The Constitution is silent on what punishment is considered to be  cruel and unusual, it has been left for the courts to determine what is and what isn't permissible under the law.  

cruel and unususal punishment

Explanation:

answer; analytical,creative and practical;