The idea that the Internet is not a (i) ______ place has become ingrained in popular culture. Because of the increasing number of users, it has become more complicated for authorities to (ii) _______ the breaches of privacy that proliferatee on a regular basis. The average user should remain (iii) _______ the exchange of personal data over the Internet.

The above highlighted are some of the clues to solve the blanks.

Starting from the second blank, it says that it is getting more complicated for authorities to __ the breaches, so the only word that fits here is limiting the breaches. Now the first blank as it is difficult to limit the breaches and the clue because indicates that the first sentence is trying to indicate the same and has a negative connotation and as there is a not already the word is positive (I used the options here) Sensible and reliable are out of scope. Thus, only secure fits the bill. Now the Last blank, As the author is warning the users in the previous sentences about the insecurity of the internet he'll continue the same. Thus, we can use cautious for the third blank.

Option B F I

Hope this helps!