问题
单项选择题
Which of the following statements about the experiment mentioned in the passage is true
A．Only the twins are defected.
B．Most of the babies are delivered by means of Caesarean.
C．There are some troubles during all mothers' pregnancies.
D．One baby appears to be abnormal.
答案
参考答案：B
解析：[分析] 是非题型。 根据第二段第四句Six of the nine were delivered by Caesarean section．推断B项正确。从第五句的意思And one baby, a twin, was born with a serious heart defect and a few days later developed life-threatening problems．可以排除A和D项。根据第二句的...the pregnancies themselves seemed to have proceeded according to plan可以排除C项。