Final answer:
Rough surfaces are best suited for subjects subject to friction as friction arises from the interaction between the roughness of two surfaces. This goes for all surfaces, including inclined planes, where the steepness of the slope affects the likelihood of slipping due to static friction.
Step-by-step explanation:
The area best suited for subjects subject to friction is 2) Rough surfaces. This is because friction arises from the interaction between the roughness of two surfaces in contact. When an object is pushed, it needs to overcome the peaks of the rough surface to start moving. The relationship between friction and the nature of the surfaces involved is clear when considering different materials, such as rubber-soled shoes, which slip less due to greater adhesion with the surface than leather-soled shoes. Moreover, frictional forces always act in opposition to motion and are crucial in understanding motion on an inclined plane. A steep incline would likely cause a wheel to slip more than a gentle slope due to the required increase in the coefficient of static friction to prevent slipping.