Final answer:
The domain of the function is -2 ≤ x < ∞.
Step-by-step explanation:
The domain of a function represents all the possible input values for the function. In this case, the function is a horizontal line between 0 and 20. Since the graph of the function is a horizontal line, the value of the function will be the same for any input between 0 and 20. Therefore, the domain of the function is -2 ≤ x < ∞, which corresponds to option C.