The ornamental design for a hook, as shown and described.
FIG. 1 is a perspective view of hook showing my new design;
FIG. 2 is a perspective view thereof from a different angle;
FIG. 3 is a right side view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a font view thereof;
FIG. 6 is a back view thereof;
FIG. 7 is a top plan view thereof;
FIG. 8 is bottom plan view thereof;
FIG. 9 is a right side view thereof showing an alternate position; and,
FIG. 10 is a left side view thereof showing an alternate position.
The broken line is for illustrative purposes only and forms no part of the claimed design.
The surface shading illustrated in the drawings is provided merely to highlight the contour of the design; it is not intended to be illustrative of texture or gloss.