Final answer:
The property of an object that is affected by a change in the body's gravitational field is mass.
Step-by-step explanation:
The property of an object that is affected by a change in the body's gravitational field is mass. Mass is the total quantity of matter in an object and it determines the strength of the gravitational interaction with other objects or gravitational fields. Unlike weight, which can vary depending on the location, mass remains the same regardless of the gravitational field.