What is the area of a rectangle with a length of 5 and a width of 4?

To find the area of a rectangle, you multiply the length by the width. In this case, the length is given as 5 units and the width is 4 units. By applying the formula for the area:

Area = Length × Width

We calculate:

Area = 5 × 4 = 20 square units.

This result indicates that the area of the rectangle is indeed 20 square units, making it the correct option. Understanding this concept hinges on recognizing that the area represents the amount of space within the boundaries of the rectangle, which is determined by this simple multiplication of its dimensions.