(A) Mobile > Devices report
(B) Site Content > Landing Page report
(C) All Traffic > Source/Medium report
(D) Technology > Network report
You can get data about Devices used to visit the site from the Devices Report. If you want to check Mobile devices specifically then you need to go to Audiences > Mobile > Devices. Here you will find all the mobile devices used to access your website.
This question is a part of the Google Analytics Individual Qualification. You can get all the answers with detailed explanation for this exam in our Google Analytics Individual Qualification Exam Answers page.