Answer:
A.
Step-by-step explanation:
The main legacy that the First World War gave to the western society was a sense of disillusionment with pre-war institutions.
The First World War brought a sense of disillusionment in a way with the challenges faced by the people. Postwar society brought with it challenges to the people to readjust. The time of peace was over and people openly questioned and criticized the involvement of leaders in the war.
Therefore, option A is correct.