Which of the following conclusions is supported by the data in the graph below?

Mathematically, choices "American History is the most popular class this summer." and "Finance is the least popular class this summer." are incorrect. Answer choice "Most students are only taking the classes that are important. " might be true, but the chart does not distinguish between important and unimportant classes, so this choice is a matter of unsubstantiated opinion. Biology has a higher percentage of enrollees than the other science classes, so answer choice "Biology is the most popular science class." is correct.