We claim the ornamental design for a sink, as shown and described.
FIG. 1 is a front perspective view of the claimed design;
FIG. 2 is a rear perspective view of the design of FIG. 1;
FIG. 3 is a front view of the design of FIG. 1;
FIG. 4 is a rear view of the design of FIG. 1;
FIG. 5 is a side view of the design of FIG. 1;
FIG. 6 is another side view of the design of FIG. 1;
FIG. 7 is a top view of the design of FIG. 1; and,
FIG. 8 is a bottom view of the design of FIG. 1.
The ornamental design which is claimed is shown in solid lines in the drawings. The broken lines in the drawings are for illustrative purposes only and form no part of the claimed design. Broken lines formed by equal length dashes show unclaimed subject matter. Broken lines formed by unequal length dashes (i.e., dash-dot) define bounds of the claimed design.