Which activity would allow NTO to build the journey with the fewest activities possible?

Northern Trail Outfitters (NTO) is building a journey which randomly sends five different versions of an initial welcome email to new subscriber however, subscribers receive the same follow-up email two weeks later. To improve maintainability of their email content, NTO want to use 3 completely different emails, rather than having one email with dynamic content.

Which activity would allow NTO to build the journey with the fewest activities possible?
A . Einstein STO
B . Engagement Split
C . Wait Until Date
D . Join

Answer: D