Answer:
6- The correct answer is D. The development of barbed wire in the 1870s changed the cattle ranching industry as it allowed owners of large ranches to enclose their territory, eliminating competition for resources.
7- The correct answer is A. Orville and Wilbur Wright are associated with the invention of the airplane.
8- The correct answer is B. The phonograph was the result of Thomas Edison's work.
9- The correct answer is D. The president that believed that a US-controlled canal across Central America was a major interest to America, and was largely responsible for construction of the Panama Canal was Theodore Roosevelt.
Step-by-step explanation:
6- Michael Kelly, of De Kalb, Illinois, patented the first barbed wire in 1868. He braided a metallic spike between two wires, and created what he called a spiny fence. With this De Kalb became the portal of entry for the cultivation of the great plains of the west. This invention allowed the great landowners to close their territory and exercise a strict control over it.
7- Brothers Wilbur and Orville Wright were two aviators, engineers, inventors and pioneers of aviation, generally named together, and recognized worldwide as those who invented, built and flew the world's first airplane successfully.
8- The phonograph was the first device to record and reproduce sounds, commonly used from the decade of 1870 until the decade of 1880. The phonograph was invented by Thomas Alva Edison, and was first in reproducing the recorded sound.
9- In foreign policy, Theodore Roosevelt advocated American expansionism, moving to control Spanish possessions in the Caribbean and the Pacific Ocean. He instigated a revolt in Panama to get the separation of that country that had previously joined the Gran Colombia in 1822 and decades later became an autonomous department of Colombia. The objective of this insurrection was to build the Panama Canal, that would be under the control of the United States. Roosevelt, a fervent supporter of the Navy, believed that the passage through the Isthmus of Panama was essential to create a strong and cohesive navy.