In 1820, US Congress reached an agreement known as ____ allowing Maine to enter the Union as"free"state one that prohibited slavery.
A. the Missouri Compromise
B. The Canadian Broadcasting Corporation
C. the Potato Famine
D. Greater London
E. the European Communities
F. Heptarchy
G. citizenship
H. Inner London
I. the Canberra Pact
J. nonstatus
K. The British Privy Council
L. status
【正确答案】：A