In a steam engine, the link constitutes a
(a) piston, piston rod and cross-head
(b) connecting rod with big and small end brasses, caps and bolts
(c) crank pin, crankshaft and flywheel
(d) all of the mentioned
This question was addressed to me in an international level competition.
My doubt stems from Kinematic Chain topic in division Simple Mechanisms of Machine Kinematics