Explain why it's that answer

Clothing junits per C Food (units per igure 4.2.2 28) Refer to Figure 4.2.2 above. Starting at point A, which of the following represents the substitution effect of an increase in the price of food? C) The move from A to B 29) When demand is elastic, an increase in price leads to: B) a decrease in total expenditures. -res. 30) A consumer has $100 per day to spend on product A, which has a unit price of $7, and product B, which has a unit price of $15. What is the slope of the budget line if good A is on the horizontal axis and good B is on the vertical axis? D) -7/15 rise 15 31) Elasticity measures: run C) the percentage change in one variable in response to a one percent increase in another variable