When Joe arrives at the library, he can choose from any of several strategies that might help him find the book he needs. He could examine all the books on every shelf, and be certain that he would eventually find the book he wants, but this strategy would take too long. Joe decides instead to ask a librarian to direct him to the appropriate section of the library. Joe is using .

A heuristic

Explanation:

A heuristic is an approach to problem solving in which previous experiences are used to develop or derive a strategy to solve a problem. This method does not necessarily mean that it will be perfect for the goal or problem, but it is sufficient to provide a quick access (like a shortcuts) to the solution given the time frame. This is the reason why Joe asked the librarian, because this would save him a lot of time, and this would provide quick access to the book he is looking for. He then banks on the experience of the librarian to help him locate the book in a very short period of time instead of examining all books on the shelf.

c, his tragic flaw to cause his downfall