※ 밑줄 친 부분에 들어갈 가장 적절한 것을 고르시오. [문 9～문 10] The first US commercial nuclear power plant started operation in Illinois in 1956. At the time, the future for nuclear energy in the United States looked A. But opponents criticized the safety of power plants and questioned whether safe disposal of nuclear waste could be assured. A 1979 accident at Three Mile Island in Pennsylvania turned many Americans against nuclear power. Furthermore, the cost of building a nuclear power plant escalated, and other, more economical sources of power began to look more appealing. During the 1970s and 1980s, plans for several nuclear plants were canceled, and the future of nuclear power remains in a state of B in the United States. A B