Your company offers public APIs with two tiers: Starter (1,000 calls/day per client) and Enterprise (10,000 calls/day per client). Developers must self-serve sign-up to obtain keys, pending approval. Each request should automatically receive a correlation ID header. What Azure API Management configuration meets these requirements with minimal overhead?

The correct option leverages Azure API Management's core features to meet all requirements efficiently. Defining two products (Starter, Enterprise) with subscription requirements directly supports the tiered access model. The rate-limit-by-key policy at the product scope enforces the daily call quotas per client. Enabling the developer portal with self-service sign-up and approval streamlines key distribution. A set-header policy at the API scope automatically injects the correlation ID. Incorrect options: Azure Front Door is a WAF and CDN, not designed for API key management or product-based rate limiting. Manual key distribution is not self-serve. Deploying two separate APIM instances is high overhead and unnecessary. Azure Functions Proxies are for simple routing, not a full API management solution with product tiers and developer portals. Implementing throttling in code increases development and maintenance effort. A JWT-validate policy is for token validation, not rate limiting. Reading counters from Redis introduces external dependencies and complexity for a feature natively available in APIM.