Which of the following calculations is used to derive the area of a rectangle?

The calculation used to derive the area of a rectangle is based on multiplying the length of the base by the height. This is because the area measures the extent of a two-dimensional surface, and for a rectangle, this surface is essentially made up of a grid of unit squares. Specifically, the base represents one side of the rectangle, while the height represents the perpendicular distance from that side to the opposite side. By multiplying these two dimensions together, you determine how many unit squares fit within the rectangle, effectively calculating its total area.

Using addition, division, or subtraction, as in the other options, would not yield the correct measure of area. Addition merely sums the base and height without considering how they relate to forming a rectangle's space. Dividing by two calculates an average rather than an area, and subtraction does not relate to the spatial concept required to compute area. Thus, the multiplication of base by height accurately captures the necessary geometric relationship to determine the area of a rectangle.