The following questions present a sentence, part of which or all of which is underlined. Beneath the sentence, you will find five ways of phrasing the underlined part. The first of these repeats the original; the other four are different. If you think the original is best, choose the first answer; otherwise choose one of the others.
These questions test correctness and effectiveness of expression. In choosing your answer, follow the requirements of standard written English; that is, pay attention to grammar, choice of words, and sentence construction. Choose the answer that produces the most effective sentence; this answer should be clear and exact, without awkwardness, ambiguity, redundancy, or grammatical error.
Although no proof yet exists of the electromagnetic disturbances observed being the results of nuclear weapons testing, diplomats are treating the situation with utmost delicacy.（）
A. of the electromagnetic disturbances observed being the results of nuclear weapons testing
B. regarding the observed electromagnetic disturbances having been the results of nuclear weapons testing
C. that the electromagnetic disturbances observed were the results of nuclear weapons testing
D. that nuclear weapons testing resulted in the electromagnetic disturbances having been observed
E. that the electromagnetic disturbance observed were resulting from nuclear weapons testing
