Apharmaceutical company is testing a new drug. for the study, the company enrolled 200 people who had previously been diagnosed with a specific condition. half took the study drug and half took a placebo. throughout the study, the participants were routinely asked to fill out a 50-question survey. after six months, the participants on the study drug showed positive improvements in their answers. what is the best way the company could improve this study to prove more thoroughly that its medications work?

decrease the pop. of placebo subjects to be less than half of the test pop.
combine results of the survey with quant. data like blood tests and brains scans
increase the length of the survey to 100 questions to check for statistical anomalies
include test subjects who have been diagnosed with a similar condition