A recent research study of undergraduate students analyzed the effects of music on human emotions. Each of the 200 participants attended at least 1 two-hour concert of classical music per week over the course of 12 weeks of their spring semester. At the end of the experiment, all of the students filled out a questionnaire assessing their emotional state. Based on the results of the questionnaires, all of the 10 students who attended the greatest number of concerts reported lower stress levels and higher satisfaction with their lives. Also, most of the 20 students who attended the fewest number of concerts reported below-average levels of emotional comfort.

Which of the following must be true based on the evidence presented above?

Most of the 200 participants improved their emotional state and lowered their stress levels.

During each week of the experiment, the participants spent at least 2 hours less on their academic work as a result of concert attendance.

Listening to classical music for at least 2 hours per week improves the emotional well-being of the majority of young adults.

More than 6 participants attended at least 14 concerts during the course of the experiment.

At least some of the students participated in the study in order to gain free access to classical concerts.

please explain this one....

Its gotta be D with a little math.

200 students - each attend 12 concerts <-- this is the bare minimum.

Now the argument states that 20 attended minimum <-- these people must have attended 12 concerts

It also states that ALL 10 of those who attended maximum <-- these 10 couldn't have attended 13 concerts since that would mean that 180 students would have attended the maximum. Hence these must have attended at least 14 concerts. Hence over 6 students attended 14 or more concerts.