Question

image result for velocity vs. time graphs
according to the graph above, what does this object do at the 2 second mark ?
turns left
turns right
comes to a complete stop and changes direction
decreases its acceleration

Explanation:

In a velocity - time graph, the velocity's sign indicates direction (positive/negative for different directions) and magnitude indicates speed. When velocity is zero, the object stops. If velocity changes sign at a point (like at t = 2s), it means the object comes to a stop (velocity = 0) and then changes direction (since velocity's sign flips). Turning left/right isn't determined by velocity - time graph (it's about direction change in terms of velocity sign, not left/right in a spatial turn as such), and acceleration is the slope of the velocity - time graph, not directly about stopping and direction change. So the object comes to a complete stop and changes direction.

Answer:

comes to a complete stop and changes direction