您应该使用哪个维度来确定是哪些来源（例如“自然搜索”或“引荐”）在吸引用户访问您的网站？

The "Session primary channel group" (Default Channel Group) dimension is the correct choice because it categorizes traffic sources into high-level, predefined groups like "Organic Search," "Direct," "Referral," and "Paid Search." This provides a standardized and easily understandable overview of how users arrive at your site. While "Session source / medium" offers more granular detail (e.g., "google / organic"), the question asks for which sources (like "organic search" or "referral"), which aligns perfectly with the aggregated view of the default channel group. "Google Ads campaign" is too specific, only showing Google Ads traffic. "Page title and screen class" describes content, not traffic sources.