A bewit is designed to attach which of the following to a bird?

A bewit is a specialized piece of equipment used in falconry primarily for attaching bells to the tarsi (the lower legs) of a bird of prey. The purpose of the bewit is to provide a secure method for fastening the bells so that they can be used to track the bird's movements while it is in the field. The bells emit sound as the bird moves, which is helpful for the falconer to locate and monitor the bird's activity during a hunt.

While other equipment, such as jesses, leashes, and swivels, serve various important roles in falconry, they are not associated with the function of a bewit. Jesses are used to secure the bird's feet for handling; leashes connect the bird to a perch or the falconer; and swivels are typically used to prevent twisting in the leash or to facilitate the movement of the bird. Thus, the primary focus of the bewit is specifically for attaching bells, making this option the correct answer.