The ornamental design for a sink, as shown and described.
FIG. 1 is an isometric view of a sink according to one embodiment of my new design.
FIG. 2 is a front side view of the decorative sink of FIG. 1.
FIG. 3 is a top plan view of the decorative sink of FIG. 1; and,
FIG. 4 is a bottom plan view of the decorative sink of FIG. 1.
The broken lines in the figures are for illustrative purposes only and form no part of the claimed design. Applicant uses the term "isometric" to describe the general orientation of the invention in FIG. 1, although such a view may not be "isometric" as traditionally defined.