Given:
The arrow diagram of a relation.
To find:
Whether the given relation is a function or not.
Solution:
A relation is a called a function it there exist a unique y-value or unique output value for each x-value or input value.
From the given arrow diagram it is clear that y=2 and y=-1 for x=-1.
Since we have more than one value of y at x=-1, therefore, the given relation is not a function.
Hence, the correct option is B.