Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that

They believe that burning fossil fuels is the main cause of air pollution.
(Dịch: Họ tin rằng việc đốt nhiên liệu hóa thạch là nguyên nhân chính gây ô nhiễm không khí.)
=> It is believed that burning fossil fuels is held responsible for air pollution.