Refer to the exhibit. An engineer is tasked to configure a Cisco IOS-XE router using restconf. The base64 code Cisco IOS-XE router uses is 1A2B3C4D5E6F7G8H910. Which line of code must be added to…

RESTCONF APIs on Cisco IOS-XE often utilize HTTP Basic Authentication for secure access, where the username and password (or a token derived from them) are base64-encoded and sent in the 'Authorization' header with the 'Basic' scheme. Therefore, 'Authorization': 'Basic 1A2B3C4D5E6F7G8H910' correctly formats the header.

'X-XSRF-TOKEN' is an HTTP header used for Cross-Site Request Forgery (XSRF) protection, a different security mechanism not typically used for basic authentication with base64-encoded credentials.

'secure-token' is not a standard or commonly recognized HTTP header for authentication in the context of RESTCONF on Cisco IOS-XE.

'x-auth-token' is a custom header often used for token-based authentication, but for a base64-encoded credential described as 'code', Basic Authentication is the standard and most fitting method.