What component links the piston to the crankshaft?

The component that links the piston to the crankshaft is the connecting rod, which interacts primarily with the crankshaft and the piston. The correct choice in this case refers simply to the crankshaft, which is a crucial part of the engine's mechanism for converting linear motion (from the pistons) into rotational motion.

When the pistons move up and down within the cylinders, the connecting rods convert that linear movement into the rotational movement necessary to drive the crankshaft. This rotational movement is what ultimately powers the vehicle. The crankshaft also plays a key role in the overall functioning of the engine, as it connects with other components to facilitate the entire combustion process.

While the other options such as crankcase, piston rings, and cylinder are important parts of the engine, they do not directly serve the function of connecting the piston to the crankshaft. The crankcase houses the crankshaft and provides a space for oil lubrication, piston rings seal the combustion chamber and control oil consumption, and the cylinder is where the piston moves. However, they do not perform the direct linking function that the crankshaft does in relation to the piston within the engine.