You are designing a sales application comprised of multiple Azure cloud services that handle orders, billing, payments, inventory, and shipping. These services must exchange transaction information asynchronously using XML messages. Which Azure service should you recommend?

Azure Queue Storage is the correct choice because it provides a robust, asynchronous messaging solution for large volumes of messages. It's ideal for decoupling application components, allowing them to communicate reliably without direct dependencies. The requirement for XML messages is easily met, as Queue Storage can store messages up to 64 KB in size, which is sufficient for typical XML transaction data. Azure Application Gateway is a web traffic load balancer that enables you to manage traffic to your web applications, not an asynchronous messaging service. Azure Data Lake is an analytics service designed for large-scale data processing, not for transactional message queuing. Azure Blob Storage is optimized for storing large amounts of unstructured object data, like images or videos, and lacks the queuing semantics necessary for reliable asynchronous message exchange between services.