The soil profile below a lake with water level at elevation 0 m and lake bottom at elevation = -10 m is shown in the figure, where k is the permeability coefficient. A piezometer (stand pipe) installed in the sand layer shows a reading of +10 m elevation. Assume that the piezometric head is uniform in the sand layer. The quantity of water (in m3/s) flowing into the lake from the sand layer through the silt layer per unit area of the lake bed is:

• A. 1.5 × 10-6
• B. 2.0 × 10-6
• C. 1.0 × 10-6
• D. 0.5 × 10-6