Which character is the best example of a tragic hero?

a. a queen, mistreated by her husband and sons, gets her revenge by placing a terrible curse on the land. b. while searching for his place in the world, an orphan encounters many unfortunate situations before he is able to find his family. c. a young student tries to overthrow the student government after his friends abandon him. d. a vain king who values appearance over truth loses his throne and eventually his life after he tries to test the population's loyalty to him