What definition of “price” given below is wrong?

Выберите один ответ:

a. the amount of the coins or notes that you must pay in order to buy something an official piece of paper with an amount of money written on it, which you send through the post to someone, who can then exchange it for the same amount of money at a post office

b. an official piece of paper with an amount of money written on it, which you send through the post to someone, who can then exchange it for the same amount of money at a post office

c. the amount of money for which something is sold

d. the quantity of payment or compensation given by one party to another in return for goods or services