The main cause of a sync from Salesforce to Account Engagement is making field changes to a Lead or Contact record (D). This will trigger a sync of the updated fields to the corresponding prospect record in Account Engagement. Updating a formula field in Salesforce (A) will not cause a sync, as formula fields are not supported by Account Engagement. Updating a field on a Contact record that does not have an email address (B) will not cause a sync, as email address is a required field for syncing. Opening a one to one email will not cause a sync, as it is not a field change event. Reference: What Causes a Prospect to Sync from Salesforce to Account Engagement?

According to the Salesforce documentation, the editions of Salesforce that can sync with Marketing Cloud Account Engagement are: C) Professional Edition and higher. A sync between Salesforce and Marketing Cloud Account Engagement is a feature that allows users to connect and exchange data between the two platforms, such as leads, contacts, accounts, campaigns, or opportunities. A sync between Salesforce and Marketing Cloud Account Engagement can be configured by the administrator in the connector settings, and it can be customized for different objects, fields, or actions. A sync between Salesforce and Marketing Cloud Account Engagement can help users to keep their data consistent and accurate, to automate their sales and marketing processes, and to measure and optimize their performance and results. A sync between Salesforce and Marketing Cloud Account Engagement can be done with different editions of Salesforce, depending on the features and functionalities that the user needs. The editions of Salesforce that can sync with Marketing Cloud Account Engagement are: Professional Edition, Enterprise Edition, Unlimited Edition, and Performance Edition. These editions of Salesforce can sync with Marketing Cloud Account Engagement, and they can also access additional features, such as custom objects, multiple scoring categories, or B2B Marketing Analytics. The edition of Salesforce that cannot sync with Marketing Cloud Account Engagement is: Standard Edition. This edition of Salesforce does not have the ability to sync with Marketing Cloud Account Engagement, and it does not have access to the additional features that the other editions have. Therefore, the user needs to upgrade to a higher edition of Salesforce if they want to sync with Marketing Cloud Account Engagement and use the advanced features. Reference: Salesforce documentation

Email, First Name, and Last Name are not required fields in order for GoToWebinar to register a new user to an event. GoToWebinar is a web conferencing platform that allows you to host and join online meetings, webinars, and trainings. You can integrate Marketing Cloud Account Engagement with GoToWebinar using the GoToWebinar connector, which allows you to register prospects for GoToWebinar events from Marketing Cloud Account Engagement forms, landing pages, or completion actions. However, the only required field for GoToWebinar registration is Email. You can also include other fields, such as First Name, Last Name, Phone, or Company, but they are not mandatory. If you do not include these fields, Marketing Cloud Account Engagement will use the default values from the prospect's record or the connector settings.
Answer A is incorrect because Email, First Name, and Last Name are not required fields in order for GoToWebinar to register a new user to an event, as explained above. Reference: [GoToWebinar Connector], [Set Up the GoToWebinar Connector]

Form handlers are the best option if you want to integrate with a third-party system, such as a payment gateway, a survey tool, or a webinar platform. Form handlers allow you to post data to more than one location, so you can send the prospect information to Marketing Cloud Account Engagement and to the external system at the same time1. You can also use form handlers to connect Marketing Cloud Account Engagement to your existing forms on your website or other platforms

The daily system generated emails are: daily prospect activity emails (for all prospects), daily prospect activity emails (for my prospects), daily visitor activity emails, and daily prospect assignment emails. These are the emails that Marketing Cloud Account Engagement sends to users based on their preferences, which provide a summary of the activities and actions of prospects and visitors on a daily basis. Daily prospect activity emails (for all prospects) show the activities of all prospects in your Marketing Cloud Account Engagement account. Daily prospect activity emails (for my prospects) show the activities of the prospects that are assigned to you. Daily visitor activity emails show the activities of the anonymous visitors on your website. Daily prospect assignment emails show the prospects that have been assigned to you or to other users910 Reference: 9: Auto generated email - How to guide10: Customizing the System Generated Emails