A block is placed on a rough inclined plane. The angle of the incline,\[\theta \] is slowly increased from the horizontal position. At a certain angle, the block starts to slide along the plane. The angle of the incline is increased further. Consider the following graphs: (I) (II) (III) (IV) Which of the above graphs correctly depicts the variation of the fractional force, f, exerted by the plane on the block, as a function of\[\theta \]? (Assume that the block does not topple.)

• A. I        
• B. II
• C. III
• D. IV