According to the passage, what caused the United States to “pass from thoughtless, careless, heedless, reckless adolescence to grave and reflecting manhood (lines 31–33)”?
F. A difficult and controversial legal trial that captured the whole country’s attention

G. The ratification of the final draft of the constitution

H. International questioning regarding the integrity and viability of America’s government
J. The secession of the southern states and the conflict that ensued