To resolve the issue of a data extension not appearing for email sends, confirm:
Sendable Status: Ensure the data extension is marked as Sendable. This setting links the data extension to a subscriber attribute, allowing it to be used for email sends.
Configuration Check: Verify the send relationship within the data extension properties, ensuring it correctly relates to the subscriber key or another unique identifier used for email campaigns.
Reference: Salesforce Marketing Cloud Data Extension Setup

Under CAN-SPAM requirements, for each commercial send, the Marketing Cloud admin should ensure that there is a Preference Center link and a physical mailing address present in the email. This compliance is critical to allow recipients to manage their email preferences (such as unsubscribing) and to meet legal requirements by providing a physical mailing address, offering transparency and options to the recipients.
Reference: Salesforce Help - CAN-SPAM Compliance

Assigning a role to the business unit allows the admin to apply specific permission restrictions to all users in that business unit. The role defines what users can access and do within Marketing Cloud. The other options are not valid ways to accomplish this requirement.

Salesforce Sidekick
For Northern Trail Outfitters' scenario, where they need to send one of three different emails randomly to new subscribers within a journey, the most suitable activity to accomplish this with the fewest steps would be using:
B). Engagement Split
However, the correct answer for randomly distributing different email versions in a journey is not listed among the options provided under typical usage. Normally, the Engagement Split is used to branch the journey based on how subscribers interact with emails (e.g., opens or clicks).
The ideal solution for NTO's need to send one of several different emails at random would be the "Random Split" activity in Journey Builder, which is not listed in the options. Since the closest option provided that would allow for varying paths (though not randomly) is the Engagement Split, it could be considered, but it does not fulfill the requirement as described.
Therefore, based on the given options and the actual functionality needed:
There seems to be a misunderstanding in the options provided. Normally, a "Random Split" would be used in this case.
If we must choose from the available options, none directly fulfill the requirement of randomly sending different email versions with the fewest activities possible.

When encountering an issue with the availability of a desired SMS keyword such as "CELEBRATION":
Keyword Unavailability: The keyword may already be in use within another business unit within the organization, making it unavailable for use in the current context.
Solution: Check the keyword usage across all business units and, if possible, coordinate to see if the keyword can be shared or if an alternative keyword would be suitable.
Reference: Salesforce Marketing Cloud MobileConnect Documentation