Sigmoid notch is present in
a)	Femur	b)	Redius-ulna	c)	Tibia-fibula	d)	Humerus

(b)

Lower part of forelimb has two bones, an inner radius and an outer ulna. The ulna is longer and thicker. At the elbow joint, which projects beyond the radius as an olecranon process that has a deep subterminal sigmoid notch for articulation with trochlea of humerus by a hinge joint.