Which equation describes the relationship of the
graphs of f(x) and g(x)?

Answer:
Depends on which function is which...
Step-by-step explanation:
The blue graph is the same as the yellow graph but raised up 1 unit. That means either:
blue function rule = yellow function rule + 1
or
yellow function rule = blue function rule - 1
Your picture doesn't say which function is f and which is g.
If, just to pick a possibility, the blue function is g(x), then
g(x) = f(x) + 1
If the blue function is f(x), then
g(x) = f(x) - 1