下图是电解饱和NaCl溶液的实验装置，其中c、d为石墨电极。则下列有关判断中正确的是

A．a为正极、b为负极

B．c为阴极、d为阳极

C．电解过程中，d电极质量增加

D．电解过程中，氯离子浓度不变

—______ is the population of China today?

—It's about one billion, three hundred million.[ ]

A. How many

B. How much

C. What