Which of the following statement is false about breakpoint chlorination curve：( )

A、When the chlorine dosage is low, there is no residual chlorine due to the consumption by organic or inorganic compounds and microorganism in water.
B、In the second zone, chlorine reacts with ammonia, the residual chlorine is mainly chloramine. When the amount of combined residual chlorine reaches a maximum, the corresponding H point on the curve is called the peak point.
C、In the third zone, with the further increase of chlorine dosage, the chloramine decomposes.
D、In the fourth zone, CA represents combined chlorine, while CB means free residual chlorine.