We live in a time___more than ever before in history,people are moving aboutA what B when C which D where选择哪一个?为什么?

We live in a time___more than ever before in history,people are moving about
A what B when C which D where
选择哪一个?为什么?

.We live in a time when,(more than ever before in history),people are moving about.
结构：共有2个谓语动词,主句的是live.(more than ever before in history)分隔了定语从句的引导词when和people are moving about.拆分为：
1) We live in a time.
2) In a time people are moving about (more than ever before in history).
翻译：在我们生活的时代中,人们四处奔波的程度远远超过历史上的任何时期.
选项为 B