FIG. 1 is a perspective view of an ornamental design for a sink trap;
FIG. 2 is a right side view of the sink trap shown in FIG. 1;
FIG. 3 is a left side view of the sink trap shown in FIG. 1;
FIG. 4 is a rear view of the sink trap shown in FIG. 1;
FIG. 5 is a front view of the sink trap shown in FIG. 1;
FIG. 6 is a top view of the sink trap shown in FIG. 1;
FIG. 7 is a bottom view of the sink trap shown in FIG. 1;
FIG. 8 is a perspective view of another embodiment of the ornamental design for a sink trap;
FIG. 9 is a right side view of the sink trap shown in FIG. 8;
FIG. 10 is a left side view of the sink trap shown in FIG. 8;
FIG. 11 is a rear view of the sink trap shown in FIG. 8;
FIG. 12 is a front view of the sink trap shown in FIG. 8;
FIG. 13 is a top view of the sink trap shown in FIG. 8; and,
FIG. 14 is a bottom view of the sink trap shown in FIG. 8.
The broken lines shown in FIGS. 4 and 11 are for the purpose of illustrating portions of the article and form no part of the claimed design.