Hostile indians, starvation, poor leadership and government
Under Kublai Khan the Mongol empire reached its largest extension. He ruled over 24000000 km² (nearly 10000000 mi²). The empire went from China and Korea to Iran and southern Russia, from the Korean peninsula to the Danube River.
During Kublai's reign the empire was divided into four smaller Kanatos but he still remained as the Great Khan of all of them. He was actually the first Khan to successfully conquest China in 1279, making him the first Yuan ruler of the whole China. After his death, the mongols didn't elect a new Khan and the Kanatos became more independent.
Because most don’t have it
Option C, It restricted the power of Black Codes already in force is the right answer.
The Black codes in the united states were the laws that limited the freedom of African Americans. These black codes were passed by the Southern states in 1865 and 1866. Enacted in July 1868, the 14th Amendment in the constitution of America proposed the Citizenship, the Equal Protection and the Due process under the law. This Amendment was an acknowledgement to the problems related to former slaves following the American Civil War. The Equal Protection clause declared that "a state may not refuse any person within its jurisdiction the equal protection of the laws".