Final answer:
The surface area of the composite solid is calculated by adding the surface area of the base prism and the additional rectangle, resulting in 120m² which corresponds to option A.
Step-by-step explanation:
The question is asking to find the surface area of a composite solid which is the total area of all the surfaces of the solid. Since the solid consists of a base rectangular prism and an additional attached rectangle, we must calculate the surface area of each and sum them. For the base prism with dimensions 4m x 4m x 5m, the surface area is the sum of the areas of all six faces (2lw + 2lh + 2wh, where l is the length, w is the width, and h is the height). So, we calculate 2(4m × 4m) + 2(4m × 5m) + 2(4m × 4m), which equals 32m² + 40m² + 32m² = 104m². The additional rectangular section is a flat surface, thus its surface area is simply its length times its width (lw), which is 4m × 4m = 16m². Adding up both these areas gives us 104m² + 16m² = 120m², which is option A.