We can see that the function is defined for the value x = -3, and even takes this value. As well as the function increases in x values, we can see that the function will take these values to infinity.
Therefore, the domain of the function is for values from -3 (including this value) to positive infinity:

Hence, the correct option is the third option: [-3, infinity) (in interval notation.)
We need to remember that the domain is only for values of x that the function can take.