The correct option is 26 weeks.

Microsoft Defender for Endpoint retains telemetry and event data for up to 180 days which corresponds to 26 weeks. This is the maximum built in retention period for endpoint telemetry and it covers the raw telemetry used for alerts, investigations, and advanced hunting. If you require retention beyond this period you must export logs to an external archive or a SIEM for longer term storage.

52 weeks is incorrect because the service does not provide a built in retention period of a full year. The maximum native retention is 180 days rather than 52 weeks, so year long storage requires exporting data.

4 weeks is incorrect because that is much shorter than the maximum retention. Four weeks is not the platform maximum and would only apply if you intentionally retained data for a shorter time outside the product.

13 weeks is incorrect because it equals about 91 days which is less than the supported maximum of 180 days. The built in retention is longer than 13 weeks.

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