To determine which of the provided answers best describes the functional relationship shown in the graph, we would need to consider the context of typical graphs involving quantities like rainfall and time.
Given that rainfall is often represented on the y-axis and time (such as months or years) on the x-axis, the most appropriate choice from your provided options would likely be:
The two quantities are the average rainfall in inches and the month of the year.
This option suggests a relationship where average rainfall changes across different months, which is a common scenario represented in such graphs.