Explanation
To set up a real-time, API-driven way to be alerted when transactional messages fail to send out of Marketing Cloud, Northern Trail Outfitters should have an external system to receive and confirm callback and subscriptions. Callbacks are notifications that Marketing Cloud sends to an external system when certain events occur, such as message failures or bounces. Subscriptions are requests that specify which events and messages an external system wants to receive callbacks for. References:
https://developer.salesforce.com/docs/atlas.en-us.noversion.mc-apis.meta/mc-apis/transactional-messaging-api.h

Explanation
To import new contacts gathered from an external web form at high frequency into Marketing Cloud, Northern Trail Outfitters should perform a daily bulk export to SFTP for import via automation. This will allow them to batch the contacts into one file per day and import them into Marketing Cloud using an automation that runs at a scheduled time. References:
https://help.salesforce.com/s/articleView?id=sf.mc_as_import_activity.htm&type=5

Explanation
A verification activity is an automation studio activity that allows checking the record count or field value of a data extension and sending a notification email if it meets certain criteria. A filter activity is an automation studio activity that allows filtering records from a source data extension into a target data extension based on filter criteria. By using these two activities in an automation, NTO can monitor available coupon codes in their coupon data extension and send a notification email to their email specialist if the available coupon count falls below 500. An import activity is used to import data from an external file or data source into a data extension, which is not relevant for this use case. A data extract activity is used to extract data from a data extension or data view into a file, which is also not relevant for this use case. References:
https://help.salesforce.com/articleView?id=sf.mc_as_verification_activity.htm&type=5
https://help.salesforce.com/articleView?id=sf.mc_as_filter_activity.htm&type=5

Explanation
The Transactional Messaging API can be used to send email to customers who log in for the first time on a new IP. The Transactional Messaging API allows for fast and reliable delivery of transactional messages, such as password resets, order confirmations, or account alerts. The message can include information related to the login IP by using personalization strings or AMPscript variables. References:
https://developer.salesforce.com/docs/marketing/marketing-cloud/guide/transactional-messaging-api.html
https://developer.salesforce.com/docs/marketing/marketing-cloud/guide/transactional-messaging-personalization

Explanation
Two potential reasons for SMS responses getting the default keyword response rather than the appropriate next keyword response are:
Responses are not sent within the Conversation Window. The Conversation Window is a setting that defines how long MobileConnect waits for a response from a subscriber after sending an outbound message. If a subscriber responds after the Conversation Window expires, MobileConnect treats their response as a new inbound message rather than part of an ongoing conversation.
Next keyword was not specified on the outbound message. The Next Keyword is a setting that defines what keyword MobileConnect expects from a subscriber after sending an outbound message. If a subscriber responds with a different keyword than what MobileConnect expects, MobileConnect treats their response as a new inbound message rather than part of an ongoing conversation.
Responses containing "stop" in the message content will not get the default keyword response, but rather an opt-out confirmation message. Responses sent with AMPscript in body will not affect how MobileConnect handles responses, as AMPscript is only evaluated at send time. References:
https://help.salesforce.com/s/articleView?id=sf.mc_moc_conversation_window.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.mc_moc_next_keyword.htm&type=5