Can you identify this line graph?

[LightFantastic]

I recently took a test with a question like the one I have attached above. There were four line graphs (I've only included one) with four solutions (I've only included two). I do not remember the question. I am hoping someone can identify the problem, and point me in the right direction.

Things I remember,

There were no inequalities (< >).
Every ray had a different starting point (like o or 2) and extending either direction (that is either an arrow in the negative direction or the positive direction).
Every starting point was filled in completely (what you would expect with an inequality that was greater or EQUAL TO).


I did not know what to do. I assume just plug in values for x and check to see if the graph was true or not.

 

[Simon Bridge]

If we consider the number line to be an x axis, then the ray drawn is $x\geq 0$.
This does not correspond to any of the options below.

Could it be that you are asked which if the relations best fits the number-line?

i.e. a ray drawn $x\geq 0$ could be consistent with $y=\sqrt{x}$.
Which would mean it is an exercise in your understanding of the domains of functions.

Pluggig in values is one approach but you are better to use your understanding of the way the functions behave ... i.e. does the equation have an assymptote or go undefined anywhere?