Suppose that a small company is thinking of putting plants in their lobby for employees to view and enjoy. Since the plants are to be viewed by employees, the plants are non-excludable (it is infeasible to move a plant each time a specific individual walks by) and non-rival in consumption (if one worker looks at the plant, it does not prevent another from doing so as well).

Which of the following comparisons is true? a: high school tests generally cover more material than college exams. b: your college curriculum is more fixed and standardized than your high school curriculum. c: you get more personal attention in class from your college professors than from your high school teachers. d: college professors usually don't review test material in class the way high school teachers do.