Which of these factors is likely to have the greatest influence on purchases by consumers with a limited amount of cash on hand?

A) The price of a good or service

B) The price of alternatives or substitutes

C) Their own income

D) Their personal preferences

B because when alternatives are cheaper and the consumer has little money, that matters more than the actual price of the good or service (A). C is wrong because we don't know the price of the item and the income doesn't matter. D is wrong because if you have limited money, your personal preferences will matter less.