Cascade Tunnel, the longest railroad tunnel in the United States, located in central Washington about 60 miles (100 km) east of Seattle.
Answer:
Cohort study
Explanation:
Cohort study: The cohort study is defined as a longitudinal study that takes a sample of cohort that performs a cross-section at different intervals concerning time.
In this context, the cohort is known as a particular group of individuals who incorporates a defining character, usually those individuals who have accomplished a specific event in a particular period, like birth order.
Cohort study comes under the observational studies.
Example: In the question above the researcher wants to identify the impact of cholesterol on the development of heart disease.
Answer:
Europeans were interested in spices from Asia, but Muslims and Italians controlled the trade routes from Asia to Europe.
New knowledge
Wealth
Fame
Adventure
Nations wanted to claim new lands and riches for themselves.
Desire to spread Christianity.
Explanation:
Many people in the south made living by growing on the land cotton tobacco and exported lumber.