(A) Behaviour > New vs returning report
(B) Behaviour > Frequency and Recency report
(C) Interests > Affinity categories report
(D) All traffic > Referrals report
You can check the percentage of traffic that previously visited your website by going to the Audience Report, then Behaviour report and then New vs Returning report. The steps are Audience > Behaviour > New vs Returning. This report will show the number of new users, returning users, the number of sessions by each, bounce rate, pages/session and avg. session duration.
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.