Please help very confused!

6. DETAILS MY NOTES A rectangular box is to have a square base and a volume of 27 fts. If the material for the base costs 9 cents per square foot, material for the top costs 3 cents per square foot, and the material for the sides costs 6 cents per square foot, determine the dimensions of the square base (in feet) that minimize the total cost of materials used in constructing the rectangular box. 1-by-1 3-by-3 2-by-2 5-by-5 B-by-8