Which of the Following Is the Best Example of a Marginal

Which of the following is the best example of a marginal change?

A) The price of water rose in Calgary by 2% last year.
B) Kim gets a big promotion at work. She also gets a raise from $25,000 per year to $40,000 per year.
C) Mark graduates from university and takes a job. His income increases from $10,000 per year to $50,000 per year.
D) A drought hits Saskatchewan and the price of wheat increases from $4.00 per bushel to $8.00 per bushel.