单项选择题

进行物质流动定量分析应遵循以下哪种定律( ) Which of the following ( ) should be obeyed in quantitative analysis of material flow( )

A、物质守恒定律 Law of mass conservation
B、牛顿运动定律 Newton"s law of motion
C、热力学定律 Law of thermodynamics
D、生态学定律 Law of ecology