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.
A council of ecologists in Hawaii have concluded that much of the currently uncontrolled invasive species on the island chain were arriving in the holds of cargo ships.（）
A. have concluded that much of the currently uncontrolled invasive species on the island chain were arriving
B. has concluded that many of the currently uncontrolled invasive species on the island chain arrived
C. have concluded that many of the currently uncontrolled invasive species on the island chain have arrived
D. concluded that many of the currently uncontrolled invasive species on the island chain would arrive
E. has concluded that much of the currently uncontrolled invasive species on the island chain had arrived
