Explanation
The correct answer is C because the last step of the 12A2 design methodology is to list the outputs of the playbook design. The outputs are the expected results or outcomes of the playbook execution, such as sending an email, creating a ticket, blocking an IP, etc. The outputs should be aligned with the objectives and goals of the playbook. See Splunk SOAR Certified Automation Developer for more details.

Explanation
The Files tab on the Investigate page allows the user to upload, download, and view files related to an investigation. A user can upload the output from a detonate action to the Files tab for further investigation, such as analyzing the file metadata, content, or hash. Files tab items and artifacts are not the only data sources that can populate active cases, as cases can also include events, tasks, notes, and comments. Files tab items can be added to investigations by using the add file action block or the Add File button on the Files tab. Phantom memory requirements may increase depending on the Files tab usage, as files are stored in the Phantom database. Reference, page 23.

Explanation
The Phantom API command to create a custom list is phantom.create_list(). This command takes a list name and an optional description as parameters and returns a list ID if successful. The other commands are not valid Phantom API commands. phantom.add_list() is a Python function that can be used in custom code blocks to add data to an existing list. Reference, page 5.

Explanation
The default embedded search engine used by Phantom is the Embedded Elastic search engine. This engine provides fast and scalable search capabilities for Phantom data. The other options are not valid search engines for Phantom. See [Search engine configuration] for more information.

Explanation
The correct answer is C because artifacts are the simplest way to pass data between playbooks. Artifacts are data objects that are associated with a container and can be created, updated, or deleted by playbooks. Artifacts can be used to store and share information such as indicators, evidence, or action results between playbooks.
The answer A is incorrect because action results are not a way to pass data between playbooks, but a way to receive data from an action within a playbook. The answer B is incorrect because the file system is not a way to pass data between playbooks, but a way to store and access files on the Phantom server or a remote host.
The answer D is incorrect because the KV Store is not a way to pass data between playbooks, but a way to store and retrieve key-value pairs on the Phantom server. Reference: Splunk SOAR Playbook Development Guide, page 30.