Answer:
C
Explanation:
Westward expansion, the 19th-century movement of settlers into the American West, began with the Louisiana Purchase and was fueled by the Gold Rush, the Oregon Trail and a belief in "manifest destiny."
Answer:
vaccination
Explanation:
Louis Pasteur had been working to find a vaccine that would cure cholera in chickens. His lab assistant gave an older, weaker strain of the disease to the birds. When these birds did not die Pasteur began to rethink his ideas a came up with our current method of administering vaccinations.
The Aswan High Dam was built to regulate and control the annual flooding of the Nile River in order to protect crops and property from such uncontrolled flooding and to generate electricity. Most of its effects have been positive but several environmental effects are:
- Water-logging: because of the continuous high levels of water, the soil around the area is saturated with water, which prevents oxygenation of the soil that is essential to several plants and crops.
- Salinization of soils: caused by the inability of water-saturated soils to absorb salt, it is toxic to crops and damaging to infrastructures.
- Soil Erosion: it is a consequence of soil salinization as crops die and are unable to hold the soil in place.
There were also other negative effects such as:
- Archeology: two important archeological sites of Ancient Egypt were flooded and covered by the dam waters: the ancient cemetery of Fadrus and the Buhen fort.
- Loss of sediment: the annual flooding carried an enormous amount of sediment that is now trapped within the resulting Lake Nasser. Many of these sediments were used by local industries to manufacture bricks and they lost access to this renewable source of raw materials.
- More expensive and difficult purification of water: because the water does not move as much it is more transparent and allows the sunlight to penetrate deeper. This, combined with the trapped sediments has increased the growth of algae that have proliferated to the point that water purification is more and more expensive due to the necessary removal of this plant.
One of the reasons that some did city-states in the Delian League revolted against Athens is because "<span>A) They resented not having a say in the government" since the heart of the government lay in the Athenian Democracy.
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