What are the three eras of military service in the United States?
A. Militia 1600s-1917, Conscript 1917-1973 & Volunteer 1973 – Present
B. Volunteer 1600s-1917, Conscript 1917-1973 & Volunteer 1973 – Present
C. Ranger 1600s-1917, Conscript 1917-1973 & Volunteer 1973 – Present
D. Militia 1600s-1941, Conscript 1941-1973 & Volunteer 1973 – Present