Our factory is much more productive now. This year’s production

Our factory is much more productive now. This year’s production is five times as much ______ it was ten years ago.
A、what
B、as　　
C、that
D、than
【正确答案】：B
【题目解析】：as much as跟......一样多。句意：我们工厂现在生产效率高多了。今年的产量是十年前的五倍。