When looking at the percentage of patients whose symptoms were relieved after taking a placebo, a scientist sees a 20% success rate. The success rate of patients whose symptoms were relieved after taking a new composite drug was 30%. The scientist determines that the margin of error is 10%, which indicates that the new drug had no statistically significant positive effect. In which stage of the engineering process is this scientist?

A. Evaluating test results
B. Screening
C. Identifying a need
D. Looking for future improvements