Which of the following is the most sophisticated experimental design?

A) ex post facto
B) ad hoc
C) Solomon Four-Group
D) pretest posttest
E) random assignment

The Solomon Four-Group experimental design is considered the most sophisticated design because it allows researchers to control for more variables and address more research questions than other designs. This design involves four groups of participants: two groups that receive the treatment with a pretest and posttest, and two groups that do not receive the treatment with a pretest and posttest. This design allows for comparisons between groups that received the treatment with and without a pretest, as well as comparisons between groups that did not receive the treatment with and without a pretest.