Answer: A. single-minded.
In MobyDick, we meet Ahab. He is a captain obsessed with killing MobyDick, a great whale. Ahab's speeches are often long-winded and tormented, and his obsession is obvious. He is single-minded, and believes that it is his destiny to kill the whale, which is the embodiment of evil in the world. He is a tragic character, because his overconfidence leads him to defy common sense and expose himself to great tragedy.