The preview matches feature in Pardot ' s automation rule setup is an essential tool for ensuring that the criteria set for a rule accurately targets the intended prospects. Before activating the rule, this feature allows the administrator to verify which prospects currently match the specified criteria without affecting the database or running the rule prematurely. This method is effective for refining and confirming criteria to avoid unintended targeting and to refine the selection process.

By default, Marketing Cloud Account Engagement will sync with contact accounts in Salesforce. Contact accounts are the standard account type in Salesforce, where each account can have multiple contacts related to it. Marketing Cloud Account Engagement can sync with contact accounts and their related contacts, leads, and opportunities. However, Marketing Cloud Account Engagement can also sync with person accounts in Salesforce, if they are enabled in your org. Person accounts are a special account type in Salesforce, where each account is also a contact. Marketing Cloud Account Engagement can sync with person accounts and their related opportunities, but not with leads. To sync with person accounts, you need to enable the option in the Salesforce connector settings in Marketing Cloud Account Engagement. For more details - > 121314

Explanation
When an opportunity is created in Marketing Cloud Account Engagement from the sync with Salesforce, the campaign that is set on the opportunity is the first campaign of the first contact associated with the opportunity. This means that Marketing Cloud Account Engagement will look at the contact roles of the opportunity in Salesforce, and find the contact that was added first. Then, Marketing Cloud Account Engagement will look at the campaign history of that contact, and find the campaign that was assigned first.
That campaign will be the one that is associated with the opportunity in Marketing Cloud Account Engagement. This helps Marketing Cloud Account Engagement track the source and influence of the opportunity. For more details -> 678

You can use an automation rule to opt out prospects by changing their field value of 'Do Not Email' to 'true'. This will prevent them from receiving any email communication from you. You cannot use an automation rule to change the field value to 'Opt-out', since that is not a valid option for the 'Do Not Email' field. You also cannot use an automation rule to opt out prospects by changing any other field value, since the 'Do Not Email' field is the only one that controls the opt-out status of prospects. Reference: [Automation Rules], [Opt Out Prospects]

Marketing Cloud Account Engagement offers three webinar connectors: Adobe Connect, ReadyTalk, and GoToWebinar. These connectors allow you to integrate Marketing Cloud Account Engagement with these web conferencing platforms and register prospects for webinar events from Marketing Cloud Account Engagement forms, landing pages, or completion actions. You can also sync webinar data, such as registrations and attendance, between Marketing Cloud Account Engagement and these platforms and use them for segmentation, automation, and reporting. Marketing Cloud Account Engagement does not offer webinar connectors for WebEx or AnyMeeting.
Answer A and E are incorrect because Marketing Cloud Account Engagement does not offer webinar connectors for WebEx or AnyMeeting, as explained above. Reference: [Webinar Connectors], [Set Up Webinar Connectors]