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.
-What is the explanatory variable in the study?

A) Getting a cold (or not)
B) Taking Vitamin C (or a Placebo)
C) Getting 8 hours of sleep a night (or not)
D) Exposure to other people with colds (or not)