单项选择题

For the most part, shopping online is as safe as shopping at your local mall. As long as you know what to look out for, there’s no reason to battle traffic or long lines when you can just as easily order what you want at home.
There are, though, some ways to make ordering online a little bit safer. Here are some tips.
Never click links in E-mails from strangers. Fraudsters (骗子) send E-mails with links to sites that look like genuine shopping sites but are actually designed to steal personal information. It’s safer to find a site through a web search or to shop online at a familiar store.
Check the protections offered by your credit card. Some cards offer 100 percent fraud (诈骗) protection, so if you do fall victim to frauds, they will cover the cost as long as you report it within a reasonable time frame.
Besides, card issuers often monitor spending activity so they can notice when something unusual happens, such as a big expenditure at a store not previously shopped at. "Visa continually monitors accounts to detect suspicious or unusual activity. " Explains Jennifer Dodge, spokeswoman for Visa.
Use different passwords. Steven Furman, marketing director of Discover’s E-business, recommends keeping two sets of passwords, one for financial transactions (交易) and one for media sites and other less secure locations. "It’s another layer of protection, " he says. Of course, that also means more passwords to remember.

The disadvantage of having two sets of passwords is that（）

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