The ornamental design for a ring, as shown and described.
FIG. 1 is a perspective view of a ring showing my new design;
FIG. 2 is a top plan view thereof; and,
FIG. 3 is a front elevational view thereof, the rear elevational view being identical thereto.
The broken lines in the drawings illustrates portions of the ring that forms no part of the claimed design. The dot-broken lines in the drawings defines the boundary of the ornmental design and form not part of the claimed design.