In each of the following, what is the mistake that underlies the statement? Explain the mistake in terms of supply and demand and the factors that influence them.

a. Consumers are illogical because they are buying more Starbucks beverages in 2019 despite the fact that Starbucks has raised prices 10 to 30 cents per drink.

b. Consumers are illogical because they buy less at Cost-ULess Warehouse Superstore when their incomes go up.

c. Consumers are illogical for buying an iPhone 11 when an iPhone X costs less.