A. Billy Graham brought about a religious revival in the United States
Hi.
Your answer is going to be
A.) agriculture
Agriculture has been greatly effected since the beginning of the 20th century. Partly due to WW1 and WW2 thus increasing the product demand and cause price spikes.
Hope this helps! :)
Despite its importance in the integration process, little work has been done on the economic effects of naturalization in the United States.