Which is closest to the surface area of the container

SA pyramid+SA rectangular prism= total SA
Total SA= Area of the base+ area of the four rectangles+area of four triangles
Total SA= length^2+length*width*4+1/2(slant height)(length)*4
length=12, width=8, slant height=10
Total SA= (12)^2+4(1/2*12*10) +4(12*8)=768cm^2
so C is correct.

Is there a picture because i cannot answer it sorry