A Research Group Hypothesizes That Diet Influences the Distribution of Bacterial

Multiple Choice

A research group hypothesizes that diet influences the distribution of bacterial species inhabiting the human digestive system.The researchers define two populations with very different diets-one in England and another in Africa-for sample collection.They take fecal samples from each group and measure the percentage of each species of bacteria present in the samples.How is this investigation classified and why?

A) This investigation is a controlled investigation because it was carried out using defined study populations.
B) This investigation is a controlled investigation because controlled methods were used for the collection and analysis of fecal samples.
C) This investigation is a comparative study because it compares a characteristic of two different groups that could be influenced by many variables.
D) This investigation is a comparative study because it tests a hypothesis that was formulated by comparing the diets of two populations.
E) This investigation is both a controlled and comparative study because it controls all but one variable influencing two study groups and then compares how that variable differs.