Consider the following statements pertaining to boundary layer:
1. Boundary layer is a thin layer adjacent to the boundary where maximum viscous energy dissipation takes place.
2. Boundary layer thickness is a thickness by which the ideal flow is shifted.
3. Separation of boundary layer is caused by presence of adverse pressure gradient.
Which of these statements are correct?
a. 1, 2 and 3 b. 1 and 2
c. 1 and 3 d. 2 and 3