出厂水中游离余氯的含量标准为______。
A.≥0.2mg/L且≤4mg/L "
B.≥0.3mg/L且≤5mg/L "
C.≥0.2mg/L且≤5mg/L
D.≥0.3mg/L且≤4mg/L "
正确答案是D