Arrange the following preparations in increasing order of their resisting area

The resisting area decreases as the preparation taper increases. For a cylinder with no taper, the resisting area would cover half the axial walls (A). For an deafly-tapered tooth preparation, the resisting area covers somewhat less than half the axial walls (B). An over-tapered (20 degrees) preparation has only a small resisting area near the occlusal surface (C).