20 teeth
By the time the embryo is eight weeks old, there are ten buds on the upper and lower arches that will eventually become the primary dentition. These teeth will continue to form until they erupt in the mouth.
Answer:
Prospective cohort study
Explanation:
Prospective cohort study is a type of observational study in epidemiology, where the subjects of the study are followed and monitored by the researcher over time, so as to investigate their risk or susceptibility to the disease. This is unlike the retrospective study where the researcher refers back in time to archived data.
The experiment described above is a prospective cohort study because the researcher follows the participants (the workers) over a span of time (ten years). At the end, he tried to evaluate the association between the exposure to the pesticide and the disease.
