软土基深基坑不放坡开挖时边坡支护可采用（）等方案。

A.地下连续墙

B.地下连续墙与土层锚杆

C.钢板桩支撑

D.钢板桩与水平钢横撑

E.挡土灌注桩与土层锚杆

Dina Borzekowski made a study of a group of third-grade students from six American schools. During a school year, nearly 400 students and their parents were asked to report on whether they had such things as televisions and computers in the home, as well as how often the child used them. The children’s language ability was tested (测验) twice over the year. Children who had a television set in the bedroom but did not have a computer at home scored (得分) the lowest, while students without TV in the bedroom but with a computer at home scored the highest. Students who had a television in the bedroom over the school year scored lower than those who had their TV taken away during the same time.
"This study suggests that taking TV sets out of children’s bedrooms, or not putting them there, may be helpful," said Borzekowski. "While this study does not prove (证明) that bedroom TV was the reason for the lower test scores, it suggests that children shouldn’t have TV in their bedrooms. It also suggests that a home computer may help a child’s test scores. The best way was having both: no TV in the bedroom and also a home computer to use. \

What does "it" in "it suggests that children shouldn’t ... " refer to
[A] The study.
[B] The reason.
[C] The score.