The increase in vertical stress due to the load acting at a point z=14 m from Calculate the centre to the bottom of a flexible rectangular area of 4 mx12 m in plan supporting a load of 200 N/m². The variation of Ic with m₁ and m is as follows: m1 111 1 2 3 4 4.00 0.108 0.190 0.241 0.269 5.00 0.072 0.131 0.174 0.202 6.00 0.051 0.095 0.130 0.155 7.00 0.038 0.072 0.100 0.122 A) 15 N/m² B) 20 N/m² C) 25 N/m² D) 50 N/m²