Refer to the Following Paragraph to Answer the Questions Below

Refer to the following paragraph to answer the questions below.
Joyce James tested whether the "military effort of modern industrial nations" is caused by the "electoral success by the right-wing parties" or the "popularity of nationalist beliefs" in a society. She tested the theory by looking at data on 22 large industrial nations during 1969-1999. She measured military effort as the "share of the gross national product" for military e.g. weapons, training, stationing troops) , right-wing party success by the percent of votes going to right-wing political parties in both national and local elections, and nationalist beliefs by attitude data from each nation. Data for the share of the gross national product came from the International Labor Organization, data for right-wing party power and nationalist attitudes came from previous studies by other researchers.
-In this study, the unit of analysis is

A) the nation.
B) the military program.
C) the individual.
D) the right-wing party.