Concert of classical music

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

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

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

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

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

Ethanol

Which of me following best completes the passage below?

Adding ethanol to the gasoline used in cars reduces exhaust emissions while slightly increasing evaporation from gasoline tanks in cars and service stations. These evaporative emissions are a major component of the smog found in many large cities in the hot summer months but, except in hot weather, evaporative emissions pose less of a pollution problem than exhaust emissions do. Therefore, if air pollution were the only consideration, one could conclude that -----.

(A) ethanol should be added only to gasoline intended for use in large cities

(B) the benefits of using gasoline to which ethanol has been added are greater in hot weather than in cold weather

(C) the disadvantages of adding ethanol to gasoline are likely to be outweighed by the advantages, at least in cold weather

(D) it is not necessary to work at reducing exhaust emissions in large cities

(E) adding ethanol to the gasoline used in large cities will improve air quality in the cities in hot weather