A REST API is being designed to implement a Mule application. What standard interface definition language can be used to define REST APIs?

The OpenAPI Specification (OAS) is the industry-standard, language-agnostic interface description for RESTful APIs. It allows both humans and computers to discover and understand the capabilities of a service without requiring access to source code or documentation. MuleSoft's Anypoint Platform fully supports designing, building, and managing APIs using OAS definitions.

A. Web Service Definition Language (WSDL) is the standard for describing SOAP-based web services, not REST APIs.

C. YAML is a data serialization language, a format in which an OAS definition can be written, but it is not the specification standard itself.

D. AsyncAPI Specification is a standard for defining and documenting asynchronous, event-driven APIs, not synchronous request-response REST APIs.

1. MuleSoft Documentation, "API specification format". "Anypoint Platform supports API specifications written in RAML or in the OpenAPI Specification (OAS), versions 2.0 and 3.0."

2. OpenAPI Initiative, "About the OpenAPI Specification". "The OpenAPI Specification (OAS) defines a standard, language-agnostic interface to HTTP APIs..."