In this question, the network engineer is using the RESTCONF API to update information about device interfaces. The RESTCONF API uses the YANG data modeling language and can encode data in either XML or JSON format. The appropriate headers must be set to specify the content type and the format in which the data is expected. RESTCONF API: This API allows network devices to be managed using web-based protocols, and it relies on the YANG data model to represent the configuration data. Content-Type and Accept headers: These headers define the media type of the resource. The Content-Type header tells the server what type of data is being sent by the client. The Accept header indicates the type of data that the client can receive from the server. Option A is the correct answer because it specifies the correct content type and accept headers for using XML with YANG data models in RESTCONF API calls. Reference: Cisco DevNet Documentation: RESTCONF API and YANG Models