The superlative form most scary must be used instead of the comparative form more scary since the author is indicating that among all the threats, a specific threat is the most scary.

• A. more must be replaced by most as the superlative form (most) must be used since the author is not comparing threats but stating that a single threat is the scariest
• B. The superlative form is correctly used
• C. Although the superlative form is correctly used, this choice makes the sentence unduly long; the phrase possibly, perhaps is awkward and not idiomatically correct
• D. While a superlative is used, the sentence is exceedingly awkward as the phrasepossibly the greatest scary is not idiomatic