Answer:a)Search Network
Step-by-step explanation:Search network is the tool provided by Google where the advertisements appear when there is search execute on the website or apps.The ad appears while searching is due to the keywords present in the search titles.
Other options are incorrect because display network is already taken by the user and because of that display, text and video are being accessed and Universal app contain various features which is not required in this situation.Search network along with display opt-in is not correct because it already has display network. Thus the correct option is option(a).