A change to the outside of the function notation is always an up/down or vertical change to the graph.
Answer: D
Subtracting 7 shifts the graph down by 7 units. Outside changes do what you'd expect them to do, because that change is happening after you've evaluated the function.
PS
A change inside the f(x) notation is a left/right or horizontal change to the graph and is usually opposite from what you'd expect.