Air flows at 25°C with a velocity of 6 m/s over a flat plate whose length is 40 cm. The momentum thickness at the center of the plate is (the kinematic viscosity of air is 1.562 × 10^–5 m²/s).

(a) 0.479 mm 

(b) 0.678 mm 

(c) 0.832 mm

(d) 1.08 mm 

(e) 1.34 mm