Select from: 1). spend too much 2). always believe the advertisements 3). never believe the advertisements 4). be careful not to be fooled

Read the following article and answer the question. Article: More and more advertisements appear on the Web. You have to be careful not to be fooled or tricked by the advertisements on the Internet. Something is said to be a bargain,but it isn't always cheap. And some socalled new things just have a new outside. However,shopping online is a kind of fashionable thing today. I love to buy things of everyday use,so I often get lots of information about them on Websites online. For example,if I want an MP3,I can choose my favorite one,and look for what the users like or don't like about it,and then decide whether to buy or not. And at the same time,you don't have to go to a shop or walk around a crowded shopping area,so you don't have to waste much time. The Internet is really useful for shopping,but be careful not to spend too much. Question: If you want to shop online, you should _ . Answer:
Answer:
4).