Search engines like Google, Bing, and Yahoo! have revolutionized research.
The best answer choice for this is that "they provide immediate access to information on the web".
The other choices would be wrong because...
Answer choice A, would be incorrect due to the fact that using the search engines makes it easier to access information than a library as you do not need to walk around the library looking for a book to provide you the answers to your question.
Answer choice B, would be false since the web doesn't always provide only reliable information from creditable sources. In fact, quite a few of the sources on the web that come up, are not helpful or do not assist the user in answering their questions.
Answer choice D, would be wrong since using the search engine to find information is quicker than using a card catalog, and also it does not only provide expert sources since any source of information could pop up when the user searches for it.