Inner and outer radii of a spool are `r` and `R` respectively. A thread is wound over its inner surface and placed over a rough horizontal surface. Then:
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A. Thread unwinds, spool rotates anticlockwise and friction acts leftwards
B. Thread winds, spool rotates clockwise and friction acts leftwards
C. Thread winds, spool moves to the right and friction act rightwards
D. Thread winds, spool moves to the right and friction does not come into existence