Explanation
The [[crm_deleted]] flag is a system field that indicates whether a prospect record has been deleted in Salesforce. The only action that removes this flag from a prospect record is undeleting the record in Salesforce. Re-submitting a form by a prospect, unchecking "CRM Deleted" on the prospect record, or removing the prospect from the Marketing Cloud Account Engagement recycle bin will not remove the flag, as the prospect will still be deleted in Salesforce2. References: 2: [System Fields]

You can delete a prospect through the prospect table actions. The prospect table is a list of all the prospects in your Marketing Cloud Account Engagement account, which you can access by navigating to Prospects > Prospect List. From there, you can select one or more prospects and click on the Tools button to see the available actions. One of the actions is Delete, which will permanently remove the selected prospects from your Marketing Cloud Account Engagement account. You can also delete a single prospect by clicking on their name and then clicking on the Delete button on their record.
Answer A is incorrect because you cannot delete a prospect through a completion action. A completion action is a task that is performed after a prospect successfully completes a marketing element, such as a form, landing page, or custom redirect. You can use completion actions to perform various actions on prospects, such as sending emails, adjusting scores, changing campaigns, or adding tags, but not deleting them. Answer B is incorrect because you cannot delete a prospect through an automation rule. An automation rule is a criteria-based action that is triggered when a prospect matches the rule. You can use automation rules to perform various actions on prospects, such as sending emails, adjusting scores, changing campaigns, or adding tags, but not deleting them. Answer C is incorrect because you can delete prospects, as explained above. Reference: Prospect List, [Delete Prospects], [Completion Actions], [Automation Rules]

Explanation
To view a prospect's Marketing Cloud Account Engagement landing page submission activity on the syncing contact in Salesforce, an Administrator can use the following features:
* The Marketing Cloud Account Engagement Activities Visualforce page, which shows a detailed history of the prospect's interactions with Marketing Cloud Account Engagement assets, including landing pages, forms, emails, and custom redirects.
* The Salesforce Activities section, which shows the tasks and events that are logged for the contact, including Marketing Cloud Account Engagement landing page submissions. References: [Marketing Cloud Account Engagement Activities Visualforce Page], [Salesforce Activities]

Explanation
When an engagement studio action step is scheduled to send an email on a specific date, it means that the email will be sent to all prospects who reach that step on or after that date. Therefore, a prospect arriving after the send date will be sent the email (D). The prospect will not remain on the step until a new send date is set (A), skip the Send Email step (B), or be removed from the program. References: Work with Time and Pauses in Engagement Studio