Conclusion: internet search users would benefit from taking the time to learn how to opt out of search history tracking.
Which of the following must be assumed to believe the conclusion about opting out of search history tracking?
A. Search engines are capable of recording an unlimited amount of any individual’s search history. -> It is not linked with the conclusion. Incorrect.
B. Internet users find it not inconvenient to receive advertising in their search results. -> Incorrect, as we don't talk about how "inconvenient" it is.
C. Regular advertising in search results is a frequent complaint of many internet users. -> Irrelevant.
D. Ignoring targeted advertising is not significantly less time consuming than learning how to opt out of such advertising. -> So, if you ignore, you won't save more time, so why don't you learn. It makes sense. Let's keep it.
E. The complexity of search engine opt out steps is intentionally high, since search engines derive revenues from the number of viewers they deliver to advertisers. -> Irrelevant.
SO, I think D.