Answer:
Ahab has always been somewhat mad, but his insanity has recently flourished.
Step-by-step explanation:
This is the statement that best describes the meaning of the excerpt. In this excerpt, we learn that Ahab has always had a type of insanity. However, we also learn that this insanity has recently become much more intense and difficult to deal with. We learn that Ahab has recently become obsessed with one particular thing, and that his lunacy has become a thousand times more intense than it had ever been before.