Einstein Recommendations uses data extensions to store user-facing information How is this data passed to Marketing Cloud?

An entertainment company is hosting events across the country in different venues. They want to use Contact Builder to feed Journey Builder. Contact who enter a journey will go through a decision split based on the type of event. The journey will send a series of emails and one of them will contain the venue details dynamically populated with AMP script.
The Company collects the following information:
- Customer data (email address, first name, last name...).
- Event registration (email address, event ID, event name, event type, venue ID...).
- Venue details (venue ID, venue name, venue address...).
- Payment details (email address, event ID, total paid...).
The Company does not want to link everything in Contact Builder.
Which are the two data sources that must be incorporated inside Contact Builder?
Choose 2 answers.

A customer is developing a new eCommerce section of their website and plans to leverage transactional data in customer journeys.
Which two Marketing Cloud features will support this effort?
Choose 2 answers

Northern Trail Outfitters wants to add new data extensions containing customer purchases to their Marketing Cloud account Which value should link these new data extensions in Data Designer to the existing contact records?

Northern Trail Outfitters installed Query Studio for Marketing Cloud, however, users are reporting they do NOT have access How should the Marketing Cloud admin ensure users have access?