This depends on your age and what language you are trying to learn really. Think about it this way, when you were born, how long did it take you to learn English (or your native tongue)? About five years right? This also depends on a bunch of other different factors like how much you practice, your determination, and the fluency of the language your speaking. So really there is no real definite answer because all people are different, but if I were to say, I'd say about five years...
An appositive is a noun or a noun phrase that renames another noun besides= it; it can be a long or short set amount of words.
Jack London's book is a noun phrase, and the name of it White Fang is renaming it in the sentence.
The correct answer would be "D".
