In which case did the U.S. Supreme Court impose a moratorium on the death penalty in the U.S.?

In which case did the U.S. Supreme Court impose a moratorium on the death penalty in the U.S.?
A. Wilkerson v. Utah
B. Atkins v. Virginia
C. Gregg v. Georgia
D. Furman v. Georgia
Answer: Furman v. Georgia