C.friction heat would make it not slide because the road would be not wet magnetism has nothing to do with it and gravity same so the most probably answer is c.friction (sorry if I don't make sense)
I know this from OT (Occupational Therapy) Shape of the letter, Spacing between letters, Style of the letter and Signature.
The metaphor in this statement is "the great millstone" it kind of qualification word it express how big the time was.
But in reality, millstone doesn't even have a relationship with the time.
So "the great millstone" is a metaphor.
True would be your answer