The correct answer is option D. "Companies replaced hand-operated brakes with air brakes on trains". The development of air brakes on trains was a significant improvement of railroad safety. Air brakes function much more faster than hand-operated brakes, because hand-operated brakes required that the brakemen turned the brakes in one car and jump to the next to set the brakes on, and so on.
Answer:
Get raw materials
Explanation:
Their presence and colonialism was based purely on self-interest.
Demand for minerals increased after America shifted from Agrarian society to an industrial society.
Explanation:
After industrial revolution use of machines were extensive and huge which made mining possible. America is rich in minerals and metal resources huge hydraulic furnaces are used in mines in order to scarp out the silver, gold and copper which were available in abundance in America.
Mining had been active and much sought after at colonial times and after independence too. Gold rush in California made many mining facilities to be opened in America. Silver coinage promoted the silver mining industries in excavating out silver.
The main role of deficit and surplus in the competitive market are the equilibrium-the state of the market, in which the volume of demand is equal to supply. The point of intersection of supply and demand is called the equilibrium point. The volume of sales at the point of equilibrium is called equilibrium volume. The price at the point of equilibrium is called the equilibrium price.
In equilibrium, the market is balanced. The installed price suits both sellers and buyers. If the price is not equal equilibrium market is not balanced. And buyers and sellers have effective incentives to change the situation.
According to the declaration of independence governments receive their authority and power from the "citizens" or general populus, since American was founded on the principle of popular sovereignty, in which government is ultimately answerable to the people who elect its representatives.
