Which service enables developers to connect their applications and services to data and events with secure, serverless and high-performing GraphQL and Pub/Sub APIs?

• A. AWS AppSync
• B. Amazon EventBridge
• C. Amazon MQ
• D. Amazon OpenSearch Service

Answer: (A)

AWS AppSync delivers secure, serverless GraphQL APIs with real-time Pub/Sub capabilities. It lets your applications query and mutate data through GraphQL, while subscriptions provide real-time updates to clients, effectively serving as a Pub/Sub mechanism. Being fully managed, it scales automatically without you provisioning servers, and it integrates with multiple data sources (such as DynamoDB, Lambda, and Elasticsearch) while handling authentication and authorization via IAM, Amazon Cognito, or API keys. This combination—GraphQL APIs, real-time subscriptions, serverless operation, and built-in security—best fits the description. Other services don’t offer both GraphQL with real-time Pub/Sub in a serverless model: EventBridge focuses on event buses for loosely coupled integrations, MQ is a traditional managed message broker, and OpenSearch Service is a search and analytics engine.