Use the Following Information for Questions

Multiple Choice

Use the following information for questions:
Twenty volunteers were assigned at random to one of two groups (10 people in each group) . One group would take Vitamin C for two weeks, while the second group would take a placebo. At the end of the study, the proportion of colds in the two groups will be compared.
-Can a conclusion that taking Vitamin C causes a change in the risk of a cold?

A) A cause and effect relation might be concluded because the study had a control group.
B) A cause and effect relation might be concluded because the study was a randomized experiment.
C) A cause and effect relation cannot be concluded because the study was an observational study.
D) A cause and effect relation cannot be concluded because exposure to other people with colds was not controlled.