Solution:
Given that;
The equation represents the function f, and the graph represents the function g.
Where

To find the slope of g(x), we will pick points on the graph

The formula to find slope, m, is

Substitute the values of the variables into the formula above

The slope of g(x) is 3
The slope of f(x) is 6,
Where,
Rate of change is the same as the slope of the function/graph
The relationship between the rates of change of f and g will be

Hence, the rate of change of f is twice the rate of change of g (option D)