The question seems to be asking for a visual representation of relations as mapping diagrams, but since there are no images provided in the text, I can't directly determine which diagram shows a relation that is not a function.
However, I can explain how to identify a relation that is not a function:
A relation is considered a function if every element in the domain is associated with exactly one element in the range. In the context of a mapping diagram, this means that each input (domain) should have exactly one output (range).
If any element in the domain maps to multiple elements in the range (i.e., there are multiple arrows leading from one point in the domain to different points in the range), that relation is not a function.
If you have access to the images of the mapping diagrams, look for a scenario where one element from the domain has two or more arrows leading to different elements in the range; that will indicate a relation that is not a function.