The angle of internal friction of soil mass is the angle whose_______________?

A. Tangent is equal to the rate of the maximum resistance to sliding on any internal inclined plane to the normal pressure acting on the plane
B. Sine is equal to the ratio of the maximum resistance to sliding on any internal inclined plane to the normal pressure acting on the plane
C. Cosine is equal to the ratio of the maximum resistance sliding on any internal inclined plane to the normal pressure acting on the plane
D. None of these