Answer:
Graham most likely suffers from intermittent explosive disorder.
Step-by-step explanation:
When a person has intermittent explosive disorder, he will have sudden and repetitive episodes of angry, aggressive behavior. His reaction to something will be out of proportion, and the violence involved can affect his personal and social relationships. The description of Graham's behavior is consistent with that of intermittent explosive disorder. Notice how his anger and imagined reaction - breaking windshields - is out of proportion in relation to the event - being stuck in traffic.