Direction: The following sentence test correctness and effectiveness of expression. Part of each sentence or the entire sentence is underlined; beneath the sentence are five ways of phrasing the underlined part. Choice 1 repeats the original phrasing; the other four choices are different. If you think the original phrasing produces a better sentence than any of the alternatives, then select choice 1; if not, select one of the other choices.

Of all the possible disasters that threaten America, the possibility of a terrorist attack is maybe the more difficult for prediction.