Which two options are valid metadata types related to deployment of external objects?

Universal Containers (UC) has integrated with their on-premise billing system using Salesforce Connect. The data is configured using an External Object in sandbox. UC wants to deploy the external object to production using the Metadata API and would like to know what Metadata types to choose for deployments to production.

Which two options are valid metadata types related to deployment of external objects? Choose 2 answers.
A . In change sets, external objects are included in the custom object component.
B. In the Metadata API, the External Object metadata type represents external objects.
C. In change sets, external objects are included in the External Object component.
D. In the Metadata API, the Custom Object metadata type represents external objects.

Answer: A,D