What item minimizes kinking and/or twisting of the anchor chain?

The item that minimizes kinking and/or twisting of the anchor chain is a swivel. Swivels are designed to allow the anchor chain to rotate freely, which is crucial when the boat is moving or when the anchor is under strain. This rotation helps to prevent the chain from twisting or kinking, which can lead to issues in anchoring performance and can also cause damage to the chain or anchor system. By incorporating a swivel into the anchoring setup, the forces exerted on the chain can be managed more effectively, resulting in a more reliable and safer anchoring situation.

In contrast, the other choices do not specifically address the issue of kinking and twisting in the same manner. Thimbles provide a way to protect the rope or chain at connections, shackles serve as connectors in the anchoring system, and anchor shanks are part of the anchor assembly that provides the holding power. None of these components, while important for different reasons, directly contribute to reducing the twisting or kinking of the anchor chain like a swivel does.