Which dimension should you use to determine which sources, such as "organic search" or "referral," are driving users to your website?

You should use Session primary channel group (Default Channel Group) is correct because this dimension categorizes incoming traffic into standard channels like Organic Search, Referral, Direct, or Paid Search, allowing you to see which sources are driving users to your website. It provides a higher-level, organized view of traffic origins compared to individual sources or campaigns, making it easier to analyze overall channel performance, whereas Page title, screen class, or Google Ads campaign focus on content or specific campaigns rather than the broader traffic channel.