Answer: 1b - 2a - 3c
Explanation:
1b
The warriors of Maya and Aztec could, as officers, in the event of proving themselves in the battle advance to higher ranks, courage was greatly appreciated.
2a
The Mayan civilization collapsed in the ninth century. The causes of the collapse are a great mystery to historical science, but most likely the poor farming system is the cause of the collapse of this civilization.
3c
The Incas built their settlements on high ground, which made it difficult for the conquerors to find them. Thus, the most famous city of the Inca Machu Picchu was found only in the twentieth century, moreover in 1911, which is enough to say how skilled they were in hiding and building.
Answer: Air brakes
Explanation: The introduction of air brakes by George Westinghouse marked one of the most important safety upgrades in railroad travel. The air brakes which is powered by compressed air connected to the braking cylinders which automatically serves air to the brake pipes once the brake pressure falls. This automatic airbrakes offered an escape from the inefficient and manual brake system usually employed before it's invention whereby brakemen are charged with the task of controlling the braking system using the brake wheel in other to alt the train's movement. This manual method is both tedious and unsafe.
West Pakistan and East Pakistan
It was his campaign against British Control of salt production
Answer:
Slavery was so profitable, it sprouted more millionaires per capital in the Mississippi River valley than anywhere in the nation. With cash crops of tobacco, cotton and sugar cane, America's southern states became the economic engine of the burgeoning nation
Explanation:
