<span>a. a substance that is naturally found in the brain</span>
The difference between the two students that we know of is that they used a different meter stick. So the difference would be best attributed to the different tools they used.
Note, this is quite a huge difference. It's likely that one of the sticks, or both, are quite defect.
Answer: mathematics
Explanation:
Mathematics is the study of quantity, space, structure of a concerned entity or population size. A scientific experiment may be based on the analysis of variables must be having large sample size. Therefore, quantitative estimation of the results is required. Hence, a scientist requires mathematics to interpret the results of a scientific experiment.