阅读下列短文，从每题所给的A、B、C、D四个选项中选出最佳选项。
A
With at least several dozen antivirus products on the market, you may be wondering which one you should choose. There's no simple one — size — fits — all answer. But here are four things to consider before making your decision.
Do You Want Cloud Antivirus?
Unlike conventional antivirus software, cloud antivirus programs do most of their processing on the Internet rather than your computer's hard drive. Cloud antivirus programs not only have a smaller resource footprint, but they also can be quicker to respond to newly emerging malware （恶意软件）threats.
What Sort of Device and Operating System Are You Protecting?
One obvious point is that you need a program that's compatible （兼容的）with your device's operating system. This isn't as much of an issue as it once was, since many antivirus software makers offer their products for multiple platforms. Another consideration is how much memory and storage space your device has, since antivirus programs sometimes can occupy many resources.
What's Your Price Point?
If you're on a tight budget and aren't a heavy-duty computer user, you may be able to get by with using one of the numerous free antivirus programs that are available. Another popular choice is Avast Free Antivirus , which has earned high ratings from security researchers and is available for Windows, Mac, Android and iOS devices. But if you can afford it, the paid versions of the free programs often have more features.
How Much Protection Do You Need?
If you're mostly just using your computer to write emails and watch movies on Netflix, then most of the fine bells and whistles on a full-featured security suite probably would go to waste. If you're surfing the web more extensively or running a home e-commerce business, you may find that advanced features in a paid program are well worth the money.
But no matter which antivirus program you pick, online security expert Bruce Schneier
says the most important thing is that you install one, and set it to automatically update. 21. What's the feature of the cloud antivirus programs?
A. They are free.
B. They do most work on the Internet.
C. They need more memory and storage space.
D. They are compatible with all the operating systems.
22. What should you do if you're lack of money?
A. Turn to an expert.
B. Study the previous cases.
C. Choose a free antivirus program.
D. Pay for an advanced antivirus program.
23. What is the most important thing after you choose an antivirus program?
A. Updating automatically. B. Setting passwords.
C. Checking occasionally. D. Storing quickly.
