The internal surface area (in m²) of an open cuboidal tank whose internal length, breadth, and height are 31 m, 20 m, and 22 m, respectively, is:

Correct option is B

Surface Area of open cuboidal tank = lb + 2lh + 2bh = (31×20) + 2(31×22) + 2(20×22) = 620 + 1364 + 880 = 2864 m²
Explanation of options: (a) ✘ 2900 is slightly overestimated. (b) ✔ Accurate surface area using correct formula gives 2864 m². (c) ✘ 2827 is underestimated. (d) ✘ 2899 is close but still incorrect.