g Liberal theorists argued, prior to World War I, that war seemed obsolete in part because countries could not afford it. Their arguments against war did not stop there, however. Some of their other arguments even won popularity again in the 1970s. What did these include

Pacifism

Explanation:

As Eric Hobsbawm explained in The Age of Extremes, World War I happened when the European Empires were crumbling and falling into pieces. Liberal theorists opposed to war as a means of Empires to gain power over others. The economic costs clearly disfavored war but there were also the ethical and moral aspects that gained momentum prior to WW I. These aspects materialised again in the 70s (Vietnam war) when more people started to protest against the human costs of war.

with my knoladg i would say it was c

answer; /// i believe that the correct answer is (d)the huang he river valley;