For each blank select one entry from the corresponding column of choices. Fill all blanks in the way that best completes the text.

Traditionally (i) in their criticism of the hazards of nuclear power—which are undeniably pressing—many environmental groups failed to cite any viable energy alternatives; still, these very groups often (ii) the success of “green technologies,” innovations that, until very recently, were able to provide only a fraction of the power required to sustain a populace.