Surface area is a geometric property that pertains to the total area covering the exterior surfaces of a three-dimensional solid.
Let's break down the options provided:
a) The measure of the amount of space inside of a solid figure:
- This description actually refers to the volume of a solid figure. Volume measures the amount of space contained within a three-dimensional object. For example, the volume of a rectangular prism is calculated as [tex]\( \text{length} \times \text{width} \times \text{height} \)[/tex].
b) The sum of all the areas of the sides of an object:
- This description refers correctly to the surface area. Surface area is the total area of all the exterior faces or sides of a three-dimensional object. For example, the surface area of a rectangular prism is calculated by finding the area of all six faces and then summing them together.
Given these explanations, the correct answer is:
b) The sum of all the areas of the sides of an object
