Here's a problem to solve: A medical research team is trying to determine whether a cream that is rubbed on the chest will help reduce the coughing associated with a particular illness. The team conducts the research using several groups of people. Which step will most likely result in producing a dependent (responding) variable that will help validate their research?

Among the 4 following options, which is the correct answer?

- A: using a different amount of people in each trial
 
- B: writing down the names of the people in the study
 
- C: monitoring the reaction of each person in the study
 
- D: applying the same amount of cream to each person
 