To achieve a victory in Europe, the Allies needed to create an effective A sea and air attack.
B two-pronged attack.
C three-pronged attack.
D sea and ground attack.

Correct answer is C. three-pronged attack.

Explanation:

C is the correct answer because Allies had to attack Germany first of all from all sides. That is why Operation Overlord was put into motion. Anglo-American forces were to attack the German forces on the shores of Normandy while in the same other Allied forces, first of all Soviet will push forward from east and south. Eventually, this led to collapse of Axis Power.

Therefore, all other options are not correct as they were not sufficient.

At the beginning of the 19th century Oregon County included the present states of Oregon, Washington, Idaho and parts of Montana, Wyoming and British Columbia.

On 18th January, 1803, President Thomas Jefferson requested permission from Congress to explore the vast lands to the west of the Mississippi. Jefferson claimed that there were "great supplies of fur and peltry" to be obtained from the Native Americans living in this area. He argued that the expedition would provide opportunities for "extending the external commerce of the United States".

The following month Congress approved the venture that became known as the Corps of Discovery. Meriwether Lewis and William Clark were co-commander of the expedition. On 23rd September, 1806, the party arrived back at St. Louis. The 28 month expedition produced a considerable body of data concerning the topographical features of the county and its natural resources.

In the 1830s some American politicians began to argue that the United States should absorb all of North America. Lewis Linn, the senator for Missouri, called for the British to be pushed out of Oregon. In an attempt to persuade Americans to settle in Oregon he introduced a bill into the Senate granting free land as a reward for those prepared to travel across the Rocky Mountains to claim it. Other politicians argued that this legislation would result in a war with Britain and the bill was defeated.

There were several reasons why people were willing to risk the long journey to Oregon. Emigrants stressed the importance of escaping from the fever-infested swamps of Missouri and Mississippi. Francis Parkman, who interviewed a large number of emigrants and claimed that many mentioned a desire to escape from unpleasant weather conditions: "The bad climate seems to have been the motive that has induced many of them to set out."

Stories also circulated about the high quality of the crops that could be grown in Oregon. Potential emigrants were told that wheat "grew as tall as a man, with each stalk sprouting seven kernels", clover was so dense that the "farmer could barely get into the field to harvest it" and turnips were "five feet tall". In the years between 1840 and 1848 an estimated 11,512 migrated overland to Oregon Trail.

In 1848 Congress established the Oregon Territory. It was admitted as the 33rd state on 14th February, 1859. Over the next few years it became a leading producer of nuts, wheat, hay, oats and potatoes.