8.
an example of at-a-distance force would be

a. tension

b. normal

c. gravitational

d. friction

Gravitational force is an example of at-a-distance force

Option: C

Explanation:

Force has both direction and magnitude it is a "vector" quantity. Force is defined as pull or push of an object resulting it to interact with two objects. There are 'Contact forces' and 'At-a-distance forces'. If two interacting objects are not in a physical contact with respect to each other the force is exerted between these two objects called 'at-a-distance' forces. This type of forces consists gravitational forces. Some of the examples of the 'at-a-distance' forces are electrical and magnetic.