Which of the following is the best example of a marginal change? select one: a. after graduating college, audrey's income increases from $500 per month to $3,000 per month. b. morgan gets a raise at her part-time job and is now paid $7.25 per hour instead of $7.00. c. housing prices in an area increase by 40 percent when a new interstate is built that passes nearby. d. a hard freeze wipes out half of the orange crop in florida and the price of orange juice doubles.