You're finding the y value from the function here. Basically, what the function equals is the y value.
Since you're finding the y value from the x value here, and you added 5 more to the x value in g(x), this means that it was translated 5 units up, because if you increase with the y value, it means that you're moving up on the coordinate graph.
So then your answer would be the third choice: The graph of g(x) is the graph of f(x) translated 5 units up.