Which of the following is a core concept of OpenTelemetry?

Context propagation is a core concept of OpenTelemetry as it enables trace context to be passed along with requests across different services. This is essential for distributed systems where requests often traverse multiple microservices. By maintaining context during these transitions, OpenTelemetry allows for accurate tracking of request flows and dependencies, which is vital for performance monitoring and troubleshooting. Context propagation involves carrying information such as trace IDs and span IDs to ensure that all parts of a request can be correlated back to their origins, enabling detailed insights into the execution of requests across the entire system.

The other concepts mentioned, while important in their own contexts, do not encapsulate the fundamental purpose of OpenTelemetry. Data encryption is more related to securing data rather than the observability aspects that OpenTelemetry focuses on. Service discovery pertains to identifying the components of a service architecture, while cloud integration deals with spreading services across cloud platforms, both of which are more about infrastructure and deployment than about the core observability features that OpenTelemetry provides.