Which file is used to define the list of services available in an application on Adobe commerce cloud?

Was going through official Magento Certification AD0-E717 mockup test, have a doubt on one of the answer –

I selected option D but it’s showing Answer A –

Here it’s clearly saying services.yaml for the same –

https://experienceleague.adobe.com/docs/commerce-cloud-service/user-guide/configure/service/services-yaml.html#:~:text=The%20services.,Redis%2C%20and%20Elasticsearch%20or%20OpenSearch.

Can anyone please confirm the best answer here, it’s confusing as services also uses file .magento.app.yaml