It can be learned from Paragraph Five that______.A．8－hour subjects fared the best among th

It can be learned from Paragraph Five that______.

A．8-hour subjects fared the best among three groups

B．the 6-hour subjects began to decline in the middle of the study

C．half of the 6-hour subjects fell asleep at the computer

D．4-hour subjects were more impaired than 6-hour subjects

请帮忙给出正确答案和分析，谢谢！