Synchronized Data Extensions via Marketing Cloud Connect allow syncing Salesforce objects (such as Leads, Contacts) into Marketing Cloud at near real-time speeds (approximately every
15?0 minutes). To filter only customers with consent selected, they can configure a Filtered Data Extension based on the synchronized object.

Send Logging, once enabled, writes granular, per-send detail - including the exact email address and content used for each individual message - into a dedicated Send Log Data Extension that marketers can directly query for troubleshooting purposes such as verifying which address received which content on a specific send.
Because the scenario explicitly states the Send Log is already being populated and is growing in size, the natural and correct recommendation is to query that existing Send Log Data Extension directly via SQL rather than standing up an entirely separate reporting mechanism. Option A, a Filter Activity on the Sendable Data Extension, only reflects current-state subscriber data, not the historical, point-in-time send detail needed to troubleshoot a specific past send. Option B, Tracking Extracts, capture engagement and delivery-status events rather than the detailed content/address-level send record that Send Logging specifically provides - it answers a different question (did it send/open/bounce) rather than ' which exact address and content combination went out. ' Option D, Sent and Subscriber Data Views, reflect general send and current subscriber status but similarly lack the granular per-send content-and-address audit trail that Send Logging is uniquely designed to preserve. Reference: Send Logging, SendLog Data Extension.

A (Keyword opt-in and SMS Messaging) is ideal because attendees can text a keyword to opt-in, and SMS provides instant, mobile-friendly, time-sensitive alerts like safety notifications or room changes.