The displacement thickness at. Section, for an air stream \[\left( \rho \,\,=\,\,1.2\,\,\text{kg/}{{\text{m}}^{\text{3}}} \right)\] moving with a velocity of 10 m/s over a flat plate is 0.5 mm. What is the loss of mass rate of flow of air due to boundary layer formation in kg per meter width of plate per second?

• A. \[6\times {{10}^{-3}}\]            
• B. \[6\times {{10}^{-5}}\]
• C. \[3\times {{10}^{-3}}\]            
• D. \[2\times {{10}^{-3}}\]