12. explain why most studies conducted in the field of environmental epidemiology are nonexperimental.

Most studies conducted in the field of environmental epidemiology are nonexperimental because it is unethical.

Explanation:

Environmental epidemiology focuses on small groups of people considered to be at risk because they already have the diseased being investigated. It is unethical to expose people to potentially dangerous environmental agents only for an epidemiological study. This is why most of these studies are nonexperimental.

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true. earthquakes are felt whenever there is a slip around a fault in the rocks below the earth. this reorientation of faults create sesmic waves and is known as earthquake, the severity of which is measured in richter scale. these are more prominent in hilly regions as the rocks usually form faults to balance the pressures on it.

the answer is the last option or letter d)