a survey by the national council of churches showed that in 1986 there were 20736 female ministers, almost 9 percent of the nation's clergy, (twice as much as 1977)
a twice as much as 1997
b twice as manyas 1997
c double what it was in 1997
d double the figure for 1997
e a number double that of 1997's
应该选哪一个呢，请指教
多谢 | 
