The output of chemical fertilizer has been raised 5 times as against last year.

A.化肥产量比去年增长了5倍。

B.化肥产量比去年增长了4倍。

C.化肥产量比去年增长了6倍。

D.去年化肥产量增长了5倍。

正确答案：化肥产量比去年增长了4倍。