What is defined as a measure of the size of a body or region in three-dimensional space?

The correct choice describes volume, which is specifically defined as the measure of the size of a body or region in three-dimensional space. Volume is typically measured in cubic units, such as cubic meters (m³) or liters, and it quantifies the amount of three-dimensional space an object occupies.

Understanding volume is essential in various fields, including science, engineering, and everyday applications, such as determining how much liquid a container can hold or how much space an object will take up. In contrast, area refers to the measure of a surface or a two-dimensional space, capacity relates to the amount a container can hold, usually in terms of liquids or granular materials, and mass measures the quantity of matter in an object, often expressed in kilograms or grams. Recognizing these distinctions is crucial for accurately applying the concepts of geometry and physics.