What is the domain of the function on the graph?

All real numbers greater than or equal to -3

Step-by-step explanation:

Notice for which values of the x-axis the function gives a well defined y-value (indicated by the trace of the curve in blue).

There is a solid dot at the point -3 for x and -2 for y, where the trace of the function begins. That means that the function is defined by f(-3) = -2.

and all x values to the right of -3 seem to also have a well defined y value f(x) that is represented by the blue curve.

Therefore, all x values starting at -3 (including it) and to the right (larger than -3) have well defined associated y values. Such constitutes the actual Domain of f(x).

a is the right answer