Explanation
For a Salesforce Opportunity to sync to Marketing Cloud Account Engagement, the Opportunity must have a Contact Role that is syncing to a prospect in Marketing Cloud Account Engagement. A Contact Role is a way of associating a Contact with an Opportunity, and specifying their role and level of influence in the sales process. Marketing Cloud Account Engagement uses the Contact Role to link the Opportunity to the corresponding prospect, and track their engagement and influence on the Opportunity4. References: 4:
Opportunity Contact Roles

The best way to understand how many prospects are currently waiting on a step in an engagement program is to look at the tooltip above that step. The tooltip will show you the number of prospects that are currently on that step, as well as the number of prospects that have completed that step. You can also see the percentage of prospects that have taken a specific action or followed a specific path from that step. The tooltip is a quick and easy way to get an overview of the performance of each step in your program

If a form is added to a landing page, the submissions will be reported on the form. A form is a web element that allows you to collect information from your prospects, such as their name, email, or company. A landing page is a web page that you create and host in Marketing Cloud Account Engagement to showcase your products or services, offer content, or register for events. You can add a form to a landing page to capture leads or convert visitors into prospects. When a prospect submits a form on a landing page, the submission data will be recorded on the form report, which shows you the number of views, submissions, errors, and conversion rate of your form

It is not possible to create a dynamic list of all prospects who have accessed a certain file in Marketing Cloud Account Engagement. Dynamic lists are based on criteria that match prospect fields, not prospect activities. Therefore, you cannot use a dynamic list to segment prospects based on whether they have downloaded a file, watched a video, or visited a page. Option A is not correct because field value mapping has nothing to do with dynamic lists or file access. Option C is not correct because match type is irrelevant for this question, as there is no valid criterion for file access. Option D is not correct for the same reason as option C. Reference: Marketing Cloud Account Engagement Dynamic Lists for Faster Segmentation (+ 10 Examples), Create a Dynamic List - Salesforce

The two Facebook accounts that can be posted to using the Marketing Cloud Account Engagement Facebook connector are Company Pages and Personal Pages. The Marketing Cloud Account Engagement Facebook connector allows you to connect your Marketing Cloud Account Engagement account with your Facebook account, and create and schedule social posts from Marketing Cloud Account Engagement. You can post to any Facebook page that you have admin access to, such as your company page or your personal page. You cannot post to other types of Facebook accounts, such as Video Pages or Linked Instagram Pages, using the Marketing Cloud Account Engagement Facebook connector.