Wall shear stress

Question

For air flow over a flat plate, velocity (U) and boundary layer thickness (d) can be expressed respectively, as

       $\frac{U}{U_{\infty }}=\frac{3}{2}\frac{Y}{\delta }-\frac{1}{2}\left (\frac{Y}{\delta } \right )^{3}$;

$\delta =\frac{4.64X}{\sqrt{Re_{x}}}$

If the free stream velocity is 2 m/s and air has Kinematic viscosity of 1.5 $\times$10^–5m²/s and density of 1.23 kg/m³, then wall shear stress at x = 1 m, is

      (a) 2.36 $\times$ 10² N/m²

      (b) 43.6 $\times$10^–3 N/m²

      (c) 4.36 $\times$10^–3 N/m²

      (d) 2.18 $\times$ 10^–3 N/m²