Final answer:
The speed of the object is the highest at moment L.
Step-by-step explanation:
The speed of an object is the magnitude of its velocity. In the graph of position vs. time, the highest speed of the object corresponds to the steepest slope or the highest magnitude of the velocity. This occurs at the moment in time when the graph has the steepest slope, which is at point L. Therefore, at moment L, the speed of the object is the highest.