Which of the following is a characteristic of non-contact forces?

Non-contact forces are defined by their ability to exert influence without the necessity for physical touch. This characteristic allows them to act at a distance, which means they can affect objects that are separated by space. For example, gravitational and magnetic forces can pull or push objects without them needing to be in direct contact.

Other options, while related to the concept of forces, do not accurately describe non-contact forces. Forces that require direct contact would fall under the category of contact forces, which function only when objects physically interact. The notion that non-contact forces only work in a vacuum is misleading, as these forces can also operate in various environments, including within gases and liquids. Furthermore, while some non-contact forces might be weaker than certain contact forces, this is not a universal truth, as the relative strength can depend on numerous factors, including the nature of the specific forces involved and the conditions present. Thus, the ability to act at a distance remains the defining characteristic of non-contact forces.