Electrical as well as gravitational affects can be thought to be caused by fields. Which of the following is true of an electrical or gravitational field?

Options

A. The field concept is often used to describe contact force.
B. Gravitational or electric field does not always exist in the space around an object.
C. Fields are useful for understandig forces acting through a distance.
D. There is no way to verify the existence of a force field source it is just a concept.

Answer

C