To determine which mapping diagram shows a relation that is not a function, we need to understand the definition of a function. A function is a special type of relation where each element in the domain is associated with exactly one element in the range.
If in any of the diagrams you see that one element in the domain is connected to multiple elements in the range, then that relation is not a function.
Since the images in your query are not visible, I cannot analyze them directly. However, you should look for any domain element that has more than one arrow pointing to different range elements. That would be the mapping diagram representing a relation that is not a function.