The ornamental design for a bra, as shown and described.
FIG. 1 is a front view of a bra according to the design;
FIG. 2 is a front perspective view thereof; and,
FIG. 3 is a front perspective view thereof shown in an environment of use.
The portions of the bra shown in broken lines in FIGS. 1-3 do not form part of the claimed design. The broken line showing of the item in the pocket on the front of the bra and the arms, torso, neck, and head in FIG. 3 is for the purpose of illustrating portions of the environmental structure and forms no part of the claimed design.