संपर्क में आने वाली दो ठोस सतहों के बीच सीमांत घर्षण बल निम्नलिखित में से किसके सीधे आनुपातिक होता है?

Assertion (A): The coefficient of static friction is always less than the coefficient of kinetic friction. Reason (R): More force is required to start the motion of an object than to maintain its motion. Select the correct answer:

Consider the following statements regarding friction: A. Friction opposes the relative motion between two surfaces in contact. It acts only on the surface of one body. B. Friction depends on how hard the two surfaces press together. C. Static friction comes into play when we try to move an object at rest. Which of the statements given above are correct?