Answer
Graph D represents situation 2.
Work Step by Step
Graph D shows the object moving with a constant, negative, y-component velocity. To create a constant velocity, an object must be experiencing either no force, or equal and opposite forces. Situation 2 is the only situation that displays equal and opposite forces acting upon the object in the y direction. This object just happened to be traveling in the negative direction, so that's why its velocity is negative.
