In the past eight months, Raquel's income increase from $1,000 per month to $1,200 per month. Raquel and her husband usually made 16 cheese sandwiches in a month, however due to Raquel's new salary, they now only make 10 sandwiches per month. Using the mid-point formula, the income elasticity is _____ and the cheese sandwiches are ____ goods. a. 1.9; normal b. -0.4; inferior c. 0.5; normal d. -2.5; inferior