To develop the material balance equation for a volumetric geopressure gas reservoirs， the drive mechanism including（）during the productive life of the reservoir.

To develop the material balance equation for a volumetric geopressure gas reservoirs， the drive mechanism including（）during the productive life of the reservoir.
A.gas expansion
B.rock expansion
C.water expansion
D.oil expansion
正确答案：gas expansion；rock expansion；water expansion