In orthogonal turning of low carbon steel pipe with principal cutting edge angle of 90, the main cutting force is 1000N and the feed force is 800N. the shear angle is 25 and orthogonal rake angle is zero. Employing Merchants theory, the ratio of friction force to the normal force acting on the cutting tool is
(a) 1.56 (b) 1.25
(c) 0.80 (d) 0.64