Given the hypothesis that the element zinc prevents cancer, which of the following procedures BEST exemplifies the nature of scientific investigation?

A- Analyze zinc, looking for different forms

B- Do research on zinc and its uses throughout history to determine if there is evidence that zinc prevents incidence of cancer


C- Rely on testimony of friends and relatives, as well as conduct a survey to see if there is a concentration of cancer in the people not taking zinc supplements


D- Give zinc supplements to a group of rats and not to another group. After a period of time, determine if there is a higher incidence of cancer in the control group​