Epidemiological studies:
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a/can establish that a risk factor causes a disorder.
b. overcome almost all of the limitations of correlational studies.
c. are generally unaffected by the problem of the third variable.
d. provide valuable information on the prevalence, incidence, and risk factors for disorders.

d.provide valuable information on the prevalence, incidence, and risk factors for disorders.

Explanation:

The study of disease distribution among the population is called epidemiology. Epidemiological studies are important to find out which risk factor is associated with that disease.  

Epidemiological studies are also used to gather information about the prevalence, incidence, and prevention of disease. This study is helpful in understanding the frequency of any disease and its cause. Knowledge of biology, statistics, sociology, etc is required in epidemiology.

Therefore the correct answer is d.provide valuable information on the prevalence, incidence, and risk factors for disorders.

how is this health related

answer; i believe its the red blood cells; plz check first good luck