In the case study that the in-use stock of lead is estimated by top-down method, which of the following describes the main reason for establishing a quantitative relationship between lead consumption P and lead entering Use stage U

A、ThedataformaterialconsumptionismoreavailablethanthedataformaterialenteringUsestage;
B、ThematerialconsumptionprocessisclosertotheUsestagethantheprocessofmaterialenteringUsestage;
C、ItiseasiertoformamaterialIn-usestockinthematerialconsumptionprocess;
D、Materialconsumptionisindependentwiththetradevolume