Oil ( = 10 2 N s /m 2 ; = 900 kg/m 3 ) flows

Oil (μ = 10^–2 N^∙s/m²; ρ = 900 kg/m³) flows past a plate in a tangential direction so that a boundary layer develops. If the velocity of approach is 4 m/s, then at a section 30 cm downstream of the leading edge the ratio of τδ (shear stress at the edge of the boundary layer) to τ₀ (shear stress at the plate surface) is approximately 

(a) 0,

(b) 0.24,

(c) 2.4, or

(d) 24.