Question: Under which of the following situations would imposition of the death penalty most likely be justified in light of constitutional considerations?
A: A defendant, a convict in prison, stabbed a prison guard to death and by statute is mandated to receive the death penalty. 
B: A defendant kidnapped and sexually assaulted a 12-year-old girl for a week before the defendant was arrested.
C: A defendant raped his victim and then savagely beat her with a baseball bat, causing her to suffer permanent brain damage. 
D: A defendant shot and killed a police officer during an attempted bank robbery.
Please eliminate two incorrect options first, then think it step by step and choose the most proper one option.