题目内容：
Insure means to protect （21） a loss of money. Most people can budget their money so that their income will cover expected expenses （22） food，clothing，housing，and public services. But，there is no way to know （23） who will suffer a crisis（危机） such as a serious illness，fire，flood，or a car accident．Such crises usually （24） great expense. Even if people could predict crises，it would be （25）to save enough money to（26） the expenses.Insurance is a system （27） a company （28） money from many individuals and then pays certain expenses （29） one of those insured individuals is faced （30） a certain crisis．An insurance policy （31） how much the insurance costs and how much the company will pay when a policy holder is faced with a certain crisis．There are many different kinds of insurance，（32） hospital，motor-car and fire．Insurance can be rather expensive （33） most people buy insurance of some kind．Insurance is something（34） people buy and hope they will（35）need.
阅读以上资料，回答题。
请在21处填写正确答案 A．for
B．from
C．against
D．with
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答案解析：