b$)$ Now use A star search to make a search tree and give the path returned by this search technique. Is the path returned by A star search the path with least cost? lf not, give the reason why A star did not return the path with least cost in this case? Moreover, can we change one of the heuristic values, so A star is able to return the path with least cost? If yes, then which heuristic value needs to be changed? What should be the new value for this heuristic? $(10$ Marks$)$