For flow past a flat plate, if x is the distance along the plate in the direction of flow, the boundary layer thickness is proportional to
A
$$\sqrt {\text{x}} $$
B
$$\frac{1}{{\sqrt {\text{x}} }}$$
C
x
D
$$\frac{1}{{\text{x}}}$$
Correct Answer: $$\sqrt {\text{x}} $$