Which two prospect activities trigger a sync from Marketing Cloud Account Engagement to Salesforce?

According to the Salesforce documentation, the two prospect activities that trigger a sync from Marketing Cloud Account Engagement to Salesforce are: A) Submitting a form, and B) Opening an email. A form submission is an activity that occurs when a prospect fills out and submits a Marketing Cloud Account Engagement form or a form handler. An email open is an activity that occurs when a prospect opens an email sent from Marketing Cloud Account Engagement. These two activities will trigger a sync from Marketing Cloud Account Engagement to Salesforce, meaning that the prospect’s information and activity data will be updated in Salesforce. A sync from Marketing Cloud Account Engagement to Salesforce happens when a prospect is created or updated in Marketing Cloud Account Engagement, or when a prospect performs a significant activity in Marketing Cloud Account Engagement. Clicking a custom redirect or unsubscribing from email are not activities that trigger a sync from Marketing Cloud Account Engagement to Salesforce, as they are not considered significant activities in Marketing Cloud Account Engagement. A custom redirect is a trackable URL that can be used to measure and report on the clicks of any online content. An unsubscribe is an action that occurs when a prospect opts out of receiving emails from the sender. These two activities will not trigger a sync from Marketing Cloud Account Engagement to Salesforce, unless they are combined with other activities that do trigger a sync, such as submitting a form or opening an email. References: Salesforce documentation