To most of us, money is 【C2】______ but the currency of a country. But to some people, money is either the best friend or the worst demon. To 【C3】______ ,however, money is a subject for study and for something to be money, it must at 【C4】______ have the following characteristics: portability, divisibility, stability, durability and acceptability.
【C5】______ , nowadays, money has got a lot of 【C6】______ : credit cards, debit cards, access cards, IC cards, etc, but they are usually 【C7】______ plastic money or electronic money, because they are used like money. 【C8】______ a credit card, for example, you can buy books and ties, pay your restaurant bills and taxi fares. You can 【C9】______ make a small overdraft if you cannot make your 【C10】______ meet this month. "Don't 【C11】______ home without it," American Express, one of the leading credit card issuers once 【C12】______ us. For many, 【C13】______ a reminder is no 【C14】______ necessary, because the plastic money is so safe and so convenient that many people 【C15】______ leave home without cash but never without a credit card.
【C1】______

A. that
B. which
C. it
D. what