Final answer:
The volume of a box with a square base of length x and height y is given by the formula V = x²y, which corresponds to answer (2).
Step-by-step explanation:
To find the volume of a box with a square base of length x and height y, you use the formula for the volume of a rectangular prism which is the area of the base times the height. Since the base is a square with a side of length x, the area of the base is x². Multiplying the base area by the height y gives us the volume, V = x²y, so the correct answer is (2) V = x²y.