9. What is the evaluation function used in A* search?
A. f(n) = g(n) + h(n), where g(n) is the estimated cost and h(n) is the path cost to the goal
B. f(n) = g(n) - h(n), where g(n) is the path cost and h(n) is the total cost
C. f(n) = h(n), where h(n) is the heuristic function
D. f(n) = g(n), where g(n) is the depth of the search tree
E. None of the above