ACCORDING TO THE PASSAGE, AT NO PERIOD IN HUMAN HISTORY HAS THERE...

12. According to the passage, at no period in human history has there been ______. A. a population explosion of the magnitude as the one in the twenty century. B. a universal fear about the future of man. C. as comprehensive a study of population problems as the one envisaged now. D. so much consensus among nations concerning the population of the world.