gwd7-4中“---”破折号是什么意思？

Only seven people this century have been killed by the great white shark, the man-eater of the movies—less than those killed by bee stings.

A.    movies—less than those

B.    movies—fewer than have been（解释说明）省略the people that have been killed...

C.    movies, which is less than those

D.    movies, a number lower than the people

E.     movies, fewer than the ones

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看过一些帖子了 大概知道了结构  但还是不清楚“—”是干什么的……

如果E改为movies, fewer than those 是不是就对了？

希望NN指教~

求问~~

真的希望有人回答一下我的弱智问题~！

感激不尽！

在此是对前面整个句子的补充说明。