The correct answer is Setting automatic removal of items after a defined lifetime.

Setting automatic removal of items after a defined lifetime refers to the Time to Live capability in Azure Cosmos DB which automatically deletes items when their configured lifetime expires. Teams commonly use this feature to manage ephemeral data such as session state, caches, telemetry and logs. Enabling TTL at the container level provides a default lifetime and individual items can override that default with their own TTL value which helps reduce storage and indexing costs and simplifies data retention management.

Tuning queries and execution plans to lower latency is incorrect because TTL does not affect how queries are planned or executed. Query performance is managed through indexing policies and query design rather than automatic item expiry.

Defining consistency guarantees for replicated data is incorrect because consistency levels such as strong or eventual are configured separately and govern replication and read semantics rather than data lifetime.

Configuring indexing behavior for containers is incorrect because indexing policies control which properties are indexed and how indexing is performed and are distinct from TTL which only removes items after their time has elapsed.

Full AWS Practitioner Certification Question