* As per definition of API by Mulesoft , it is Application Programming Interface using HTTP-based protocols. Non-HTTP-based programmatic interfaces are not APIs.
* HTTP-based programmatic interfaces are APIs even if they don't use REST or JSON. Hence implementation based on Java RMI, CORBA/IIOP, raw TCP/IP interfaces are not API's as they are not using HTTP.
* One more thing to note is FTP was not built to be secure. It is generally considered to be an insecure protocol because it relies on clear-text usernames and passwords for authentication and does not use encryption.
* Data sent via FTP is vulnerable to sniffing, spoofing, and brute force attacks, among other basic attack methods.
Considering the above points only correct option is
-XML over ActiveMQ
- XML over SFTP
- XML/REST over HTTPS

Correct answer is Workers are randomly distributed across available AZs within that region. This ensure high availability for deployed mule applications Mulesoft documentation reference :
https://docs.mulesoft.com/runtime-manager/cloudhub-hadr

In the given scenario, a rate limiting policy has been applied to the SOAP API and a global error handler is configured to handle HTTP:RETRY_EXHAUSTED errors with a 429 status code. The rate limiting policy will trigger when the client exceeds the allowed quota of API calls. Since the HTTP:RETRY_EXHAUSTED error specifically catches quota exhaustion errors and the error handler is configured to return a 429 status code, the expected HTTP status returned to the client when the quota is exceeded will be 429. This error code indicates that the user has sent too many requests in a given amount of time ("rate limiting").
MuleSoft Documentation on Error Handling
HTTP Status Codes

Anypoint Platform offers universal API management and Integration-Platform-as-a-Service (iPaaS) capabilities in a unified platform, meaning that it provides a single control plane to manage both full-lifecycle API management and integration. This allows organizations to easily manage their APIs and integrations, as well as deploy APIs and integrations quickly and efficiently. According to the MuleSoft Certified Integration Architect - Level 1 Course Book, "Anypoint Platform provides a unified platform for managing, deploying, and monitoring both API and integration solutions, allowing organizations to quickly and easily build and manage their APIs and integrations."

In this scenario, both A & C will work, but A is better as it does not require repackage to the domain project at all.
Correct answer is Package the HTTPS Listener configuration in a Mule DOMAIN project, referencing it from all Mule applications that need to expose an HTTPS endpoint. Store the server-side certificate in a shared filesystem location in the Mule runtime's classpath, OUTSIDE the Mule DOMAIN or any Mule APPLICATION.
What is Mule Domain Project?
* A Mule Domain Project is implemented to configure the resources that are shared among different projects.
These resources can be used by all the projects associated with this domain. Mule applications can be associated with only one domain, but a domain can be associated with multiple projects. Shared resources allow multiple development teams to work in parallel using the same set of reusable connectors. Defining these connectors as shared resources at the domain level allows the team to: - Expose multiple services within the domain through the same port. - Share the connection to persistent storage. - Share services between apps through a well-defined interface. - Ensure consistency between apps upon any changes because the configuration is only set in one place.
* Use domains Project to share the same host and port among multiple projects. You can declare the http connector within a domain project and associate the domain project with other projects. Doing this also allows to control thread settings, keystore configurations, time outs for all the requests made within multiple applications. You may think that one can also achieve this by duplicating the http connector configuration across all the applications. But, doing this may pose a nightmare if you have to make a change and redeploy all the applications.
* If you use connector configuration in the domain and let all the applications use the new domain instead of a default domain, you will maintain only one copy of the http connector configuration. Any changes will require only the domain to the redeployed instead of all the applications.
You can start using domains in only three steps:
1) Create a Mule Domain project
2) Create the global connector configurations which needs to be shared across the applications inside the Mule Domain project
3) Modify the value of domain in mule-deploy.properties file of the applications Graphical user interface Description automatically generated

Use a certificate defined in already deployed Mule domain Configure the certificate in the domain so that the API proxy HTTPS Listener references it, and then deploy the secure API proxy to the target Runtime Fabric, or on-premises target. (CloudHub is not supported with this approach because it does not support Mule domains.)