Which of the following equations best expresses conservation of mass for steady, incompressible flow between two sections of a pipe having cross-sectional areas A1 and A2 and flow speeds v1 and v2, respectively?
a) A1v1=2A2v2
b) A1v1=A2v1
c) A1v1=A2v2
d) A1v1=(A1+A2)v2