Which of the following can be attached to concrete using an expansion anchor, concrete screw, or through bolt?

An eye nut is designed specifically to be attached to a structural element like concrete when using an expansion anchor, concrete screw, or through bolt. Eye nuts provide a convenient attachment point and are constructed in a way that allows for secure fastening and load-bearing capabilities. When installed correctly in concrete, they can hold significant weight and are commonly used in rigging and lifting applications.

The other options, while they are useful hardware types, do not serve the same purpose or are not meant to be directly anchored to concrete using the methods specified. Swivel hoist rings, for example, are generally used in conjunction with an attachment point but require a separate component (like a bolt) to be effectively employed. Carabiners and anchor shackles are typically used to connect various rigging components but are not designed for direct anchoring into concrete without a secure anchor system.