Answer: Option (a) is the correct answer.
Step-by-step explanation:
Static friction is defined as the friction that occurs between a stationary object and the surface on which it is resting.
For example, a box resting on a ramp is stationary and a static friction occurs between the box and the ramp.
Whereas when an object moves from one place to another then there exists kinetic friction between the moving object and the surface on which it moves.
Therefore, we can conclude that out of the given examples, a box sits stationary on a ramp illustrates static friction.