What should be selected during the Email Send flow if a marketer wants to keep the send simple and not split the audiences into two separate sends?

The choice of Multi-part MIME is the correct selection for keeping the email send simple without splitting the audience into separate sends. Multi-part MIME allows an email to be sent in multiple formats simultaneously, typically HTML and plain text. This means that recipients can receive the email in a format that is best suited to their email client or preferences without needing to create different versions of the email for different audiences.

This approach ensures that the marketer maintains a single send process, simplifying the workflow and improving efficiency. By utilizing Multi-part MIME, the email can be rendered correctly across various devices and email clients without the need for additional segmentation or audience division.

In contrast, options like Link Tracking, Transactional Sender Profile, and Hourly Send Throttle serve different purposes. Link Tracking helps in measuring engagement through links within the email, a Transactional Sender Profile is used for transactional messages that might require a different sender identity or settings, and Hourly Send Throttle controls the rate at which emails are sent to avoid overwhelming recipients or getting flagged as spam. None of these options directly address the desire for a straightforward send without segmentation, making Multi-part MIME the optimal choice.