A study was done by an online matchmaking company to determine the rate at which users used its website. A graph of the data that was collected is shown:

A line graph with Number of Months on the x axis and Number of Users, in thousands, on the y axis. The x axis has a scale from 0 to 12 with an increment of 1. The y axis has a scale of 0 to 40 with increments of 5. A straight line connecting 0, 25 and 12, 25 is drawn.

What can be interpreted from the range of this graph?

The range represents the number of users each month for 12 months.
The range represents the number of users each month for 25 months.
The range represents the 12-month time period of the study.
The range represents the 25-month time period of the study.