B) It is unnecessary to oversee the athletes involved in mixed martial arts.
The viewpoint made in section one is that "State athletic commissions should strictly monitor and regulate the UFC." A rebuttal statement is one that goes against the viewpoint, so it needs to say something about how the UFC should not be monitored or regulated. Option A agrees with the viewpoint by saying overseeing athletes is necessary. Option B states the opposite by saying it is unnecessary to oversee athletes. Therefore, this is the correct answer. Option C says that athletes must self-regulate. While this puts the responsibility of regulating on the athletes, it does not take it away from the commissions. There is nothing here to suggest that the commissions would not regulate just because the athletes are. Option D has nothing to do with monitoring or regulating so it is a poor choice.
#1 A library? The internet?
#2 Search the library catalog, they're typically organized in sections based on genre and then alphabetically (by author name). Or ask a librarian for help.
#3 You'd write the call number.
#4 It's a code that tells you where items are located and tracks the book (like if somebody else has it checked out or not)
#5 Hierarchical structure or faceted classification
Since a participle takes the form: verb + -ing, the only word in this sentence which has such a form is B, 'challenging'. 'Puzzle' is a noun, 'crossword' is an adjective, 'created' is a verb.
