Which graph does not represent a function

The graph that does not represent a function is;

The first graph of the circle

Step-by-step explanation:

A function is a relationship, rule or law that maps the inputs 'x' the input set 'X' known as the domain, to exactly one output 'y' in the output set 'Y' known as the range

Therefore, a function maps an input to exactly one output

In a graph, the inputs are usually the x-variables, therefore the graph that maps the x-variables (in which an x-variable has) to more than one y-variable is the graph of the circle

In the graph of the circle, we have;

When x = 0 at the origin, y = 0

Similarly

When x = 0 at the maximum point, y = 4

Therefore, the graph of the circle does not represent a function.