Can someone pls help ! I’m sorry it’s small

The velocity time graph which shows a negative constant velocity (horizontal line below the horizontal axis) Labeled as Graph #2

Explanation:

Notice that the position-time graph shows the position decreasing in the form of a line with negative slope. Recall that the velocity graph is associated with the change in position with time, and this change in position is in the form of a line of constant negative slope. The slope of the position-time graph is in fact the velocity of the object, which therefore is negative and constant.

Such behavior is represented by the graph labeled as Graph 2 of a constant (horizontal) line below the horizontal axis.  

no. dot product   =0 when vecs at right angles