Let's solve this problem step-by-step:
Let's examine this graph to see what information we gain:
- Graph of g(x) to graph of f(x) horizontally has no difference
- Graph of g(x) to graph of f(x) vertically has y-coordinates half the value of y-coordinates of f(x)
That means the function was stretched vertically or in the direction of the y-axis:
⇒

Thus the answer is the first choice
Answer: First choice or

Hope that helps!