Since its a sibling, and siblings tend to be in a person's close circle of people, informal speech is used.
The answer is: A. obsession
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In the excerpt from "Moby D*ck," by Herman Melville, the narrator describes Captain Ahab's determination and fixation to kill the whale that caught his leg. Thus, Ishmael mentions Ahab's upright posture, his coraugeous persistance, and devoted look towards a dangerous task like encountering the whale.
Go to eBay I did it and I worked