The requirement has two distinct needs: complex segmentation logic (six-month purchase lookback, likely joining transactional and contact data) and true omnichannel orchestration across email, SMS, and push in a single coordinated flow. A SQL Query Activity in Automation Studio is the right tool to build that segmentation, since it can join multiple data extensions and apply date-based filtering with precision. The output then feeds a Data Extension Entry Source into a journey, and Journey Builder ' s multi-channel activities (Email, SMS, Push) natively send the same coordinated message across whichever channels each contact is opted into, using the same journey path. Option A stops at Automation Studio activities, which lack native multi-channel send orchestration within a single flow. Option B ' s Decision Split without a preceding robust query risks segmentation being handled inside the journey rather than pre-filtered, and pairs oddly with an Import Activity rather than a query against existing data. Option C ' s Salesforce Entry Event is unnecessary complexity when the source data already lives in Marketing Cloud and doesn ' t require Salesforce-triggered entry. The ' Query Activity into a Data Extension Entry Source, then Journey activities ' pattern is the standard, exam-tested approach for segmented, cross-channel, one-message-many-channels campaigns. Reference: Journey Builder Entry Sources, Automation Studio Query Activity, Multi-Channel Messaging.