I believe the answer would be Bill Gates. An appositive is a noun that renames a noun right beside it. In this case, "Bill Gates" is renaming "One of the richest men in the world."
The answer is c, because it is clearly not an alliteration, and there is no repetition. An end rhyme is when words on the end of lines sentences rhyme with the words on the ends of other sentences; where as an internal rhyme has rhymes in the same sentence.
