44、 The boundary layer flow over a flat plate with zero pressure gradients is shown in Figure 44.The control volume is defined as dashed line a-b-c-d and the depth is defined as w. Ahead ofthe plate the velocity is uniform, U. The velocity distribution across cd is approximated by 

 , here 

 denotes the boundary layer thickness. Which of thefollowing statements is correct?

 
(A) the mass flux across bc equals 

,
(B) the mass flux across ab equals 

 ,
(C) the mass flux across cd equals

 ,
(D) the mass flux across bc equals