A Marginal Change Is Illustrated by Which of the Following

A marginal change is illustrated by which of the following?

A) Nancy retires and takes a part-time job. She was working 40 hours per week and now works 10 hours per week.
B) Provincial University has announced that due to provincial budget deficits, tuition must rise by 25% next year.
C) Ryan moved to a new apartment and now pays 40% more rent than before.
D) Vancouver, which usually receives 10 inches of rain per year, received 11 inches last year.