What are three ways a driver can cause a car to accelerate? A. Turn the key in the ignition while the car is stopped.
B. Turn the steering wheel while the car is moving.
C. Press the gas pedal while the car is stopped.
D. Press the brake pedal while the car is moving.

Honestly "global warming" may be a slight possiblity, however they called it "climate change" because its not real, in fact we had one of our coldest days here not too long ago, and the "issues" with this subject is a blindfold for actual problems.

Need more information like a picture

Answer(a)   the matererials that are in contact, the two materials and the nature of their surfaces/// (b)/// the force pushing the two surfaces together, pushing the surfaces together causes the more of the asperities to come together and increases the surface area in contact with each other