Air pollution has become____than ever before. We must do somethi

Air pollution has become____than ever before. We must do something to stop it.
A、serious
B、more serious
C、most serious
D、the most serious
【正确答案】：B
【题目解析】：试题分析：根据下文than ever before可知表示和以前的对比，故用形容词比较级作表语，选B。