Asynchronous calls to Salesforce are supported by which APIs?

Asynchronous calls to Salesforce are primarily supported by the Bulk API and the Streaming API rather than the REST or SOAP APIs. The Bulk API is designed for handling large volumes of data in an asynchronous manner, allowing for batch processing, which means it can process records in bulk rather than one at a time. This is particularly useful when working with significant datasets that need to be uploaded or modified without blocking user interactions.

The Streaming API allows for real-time notifications when changes occur in Salesforce data, enabling clients to receive updates in an asynchronous fashion, making it highly efficient for applications that need to stay in sync without continuously polling for changes.

The REST API, although it can perform asynchronous operations through techniques like using asynchronous processing or features like Batch, isn't natively built for asynchronous calls like the Bulk API. The SOAP API also primarily operates in a synchronous manner, where each request waits for a response, making it unsuitable for tasks that would benefit from asynchronous handling.

Thus, the choice stating that neither REST nor SOAP APIs support asynchronous calls correctly captures the limitations of these specific APIs in the context of Salesforce integration.