What is the domain of the function on the graph?

a.) all real numbers
b.) all real numbers greater than or equal to 0
c.) all real numbers greater than or equal to –2
d.) all real numbers greater than or equal to –3

Go to the left-most point on the graph. That point is (-3,-2). The x coordinate of this point is x = -3.

So the smallest x can be is x = -3. The variable x can't be any smaller. It can be larger than -3.

Since x can equal -3 or be larger, this makes the domain to be  (x is greater than or equal to -3)

In interval notation, you would write 
The square bracket tells you to include the endpoint -3 while the curved parenthesis tells you to exclude infinity as an endpoint. Plus or minus infinity is always associated with a curved parenthesis.

In short, the answer is choice D