Here's a problem to solve: Several different sized filter-paper disks are soaked in a solution and placed into another solution where a reaction will take place that produces a gas. The gas bubbles collect on the filter paper and make the filter paper rise to the top of the solution. Which of these is a measurement that would not be made during this experiment?

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

- A: the number of bubbles produced
 
- B: the distance the filter paper rises
 
- C: the diameter of the filter-paper disks
 
- D: the time it takes for the filter paper to rise
 