Apet shop had 8 identical fish tanks in the shape of rectangular prisms. the width and height of each tank was (x - 7) inches and the length was 8 inches more than its width. the expression below shows the maximum amount of water which all the tanks together can hold
8(x + 1)(x - 7)2

what does the factor (x - 7)2 represent?

the total base area of all the tanks
the total surface area of each tank
the area of the rectangular base of each tank
the area of a square shaped side of the tank