Sink

FIG. 1 is a top plan view of my ornamental design for a sink;

FIG. 2 is a bottom view thereof;

FIG. 3 is a front view thereof, the rear view is a mirror image thereof;

FIG. 4 is a left-side view thereof, the right-side view is a mirror image thereof;

FIG. 5 is a perspective view thereof; and,

FIG. 6 is a cross section of FIG. 1 along 6 - 6 .

The broken lines illustrate portions of the sink and form no part of the claimed design.

The interior and exterior surfaces of the sink design are made of contrasting materials, and the contrast in materials is illustrated by the oblique lines shading the interior surface and the parallel lines shading the exterior surface.