The ornamental design for a basket, as shown and described.
FIG. 1 is a perspective view of a basket showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is another rear view thereof with screws being installed in the basket.
The broken line portions of the basket in FIGS. 1-8 represent unclaimed portions of the claimed design and form no part thereof. The broken lines of the screws in FIG. 8 illustrate unclaimed environment and form no part of the claimed design.