The ornamental design for a bra, as shown and described.
FIG. 1 is a rear view of a bra according to the design;
FIG. 2 is a rear perspective view thereof; and,
FIG. 3 is a rear 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 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.