Suppose you conduct a scientific investigation to find out how daily intake of vitamin C affects a person's resistance to
developing flu symptoms. You test 100 people, all of the same age and same general health. You give 25 people one
vitamin tablet a day, another 25 people two vitamin tablets a day, another 25 people three vitamin tablets a day, and the
final 25 people get four vitamin tablets a day. You carry this out for two months and observe the health of all 100 people
over time. Which of the following is your experimental factor?
A. number of people studied
B. number of vitamin tablets a person gets each day
C. the age of the people in the study
D. the health of each person at the beginning of the study