Answer: D. It can be conducted with existing data
Explanation:
Cohort studies observe a number of people over a period of time to discover the factors pertaining to a disease such as its causes and effects. It can be prospective, which uses data gathered in the future or retrospective which uses data already collected.
Prospective cohort studies are useful in estimating risk and impractical for studying rare diseases due to the need for a large group. When used to identify the cause of a disease, a hypothesis is tested by monitoring a cohort for any differences in health associated with the risk factor
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Existing data. and the study of diseases with a long latency between exposure and symptoms development apply to retrospective cohort study.
There were many key elements and financial innovations that made Florence and Venice financial centres of the world, but one of the most important was the banking system that issues credit and charged interest.
Answer:
As the decrease in the tulip's quantity in the both cases is the same, hence the opportunity cost will also be the same required that the marginal cost remains constant.
Explanation:
Opportunity cost is the value lost in opting to alternative option. This means that if an ice cream costs me $10 then the opportunity cost of eating an ice cream would be $10 because I haven't enjoyed an alternative of an ice cream which would be worth $10. Likewise, if I am deciding to attend a party but I have previously purchased cinema tickets worth $50 then the opportunity cost of attending the party would be $50 and opportunity cost of watching movie would be the loss of entertainment at the party.
The opportunity cost of producing 0-300 tulips is $5 per tulip then it is more likely that the cost of producing 600-900 tulips will also be $5 per tulip.
Thus the opportunity cost here for each case will be:
Case1 0-300 Tulips: 300 Tulips * $5 per Unit = $1500
Case2 600-900 Tulips: 300 Tulips * $5 per Unit = $1500
But if the cost of producing first 300 units of tulips are different from the third 300 units of tulip then there will be of course a difference in opportunity cost.
the answer in D) his exploration led others to north america
Cardiovascular diseases such as atheroscelerosis and hypertension
Cardiovascular diseases are series of diseases that occur due to narrowed or blocked blood vessels which can result in chest pain, heart cold or stroke. Excess free radicals play an important role in the initiation and progression of cardiovascular diseases such as atheroscelerosis by damaging the blood vessel walls.
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