Dynamic lists are lists that automatically add or remove prospects based on criteria that you define. Prospects can be "unmatched" from a dynamic list if they no longer meet the criteria. For example, if you have a dynamic list of prospects who have opened an email in the last 30 days, and a prospect does not open any email for 31 days, they will be removed from the list. Automation rules and segmentation rules do not
"unmatch" prospects, they only apply actions to prospects that match the criteria

The way that a marketer can avoid emailing prospects more than once in a ten day span is to use a dynamic list to create a frequency suppression list. A dynamic list is a type of list that automatically updates based on specific criteria, such as field values, activities, or scores. A frequency suppression list is a type of list that excludes prospects who have been emailed within a certain time frame, such as ten days. By using a dynamic list with a frequency suppression criteria, a marketer can ensure that they do not email prospects who have already received an email recently. Using an automation rule, a global account setting, or a segmentation rule are not ways that a marketer can avoid emailing prospects more than once in a ten day span, as they either do not create lists, do not update automatically, or do not run continuously2. References: 2: Dynamic Lists

The reason why the reporting metrics of Email Template A are not changing as a result of the new list email send is that the metrics would be attributed to Email Template B. When a user creates a copy of an email template, makes changes and saves it as a new email template, the new email template becomes a separate entity from the original email template. The new email template has its own name, ID, and reporting metrics.
The reporting metrics of an email template include the number of sends, total opens, unique opens, total clicks, unique clicks, opt-outs, and spam complaints. These metrics are calculated based on the emails that use the email template. Therefore, when the user sends a list email using Email Template B, the reporting metrics of Email Template B are updated, but the reporting metrics of Email Template A are not affected1. Option A is not correct because an email template's metrics do change after the template is used one time. An email template's metrics are updated every time an email that uses the template is sent, opened, clicked, opted out, or marked as spam1. Option B is not correct because Email Template A should not have been deleted after creating the copy. Deleting an email template does not affect the reporting metrics of the template or the emails that use the template. Deleting an email template only prevents the template from being used for new emails1. Option D is not correct because the user should not have made Email Template A the primary template. There is no concept of a primary template in Marketing Cloud Account Engagement. Each email template is independent and can be used for different types of emails. Making Email Template A the primary template would not change the reporting metrics of the template or the emails that use the template

The list email or email template report deliverability metric that could indicate an unverified sending domain is hard bounces. Hard bounces are permanent delivery failures, such as invalid email addresses or blocked domains. Hard bounces can negatively affect the sender reputation and the email deliverability. One of the possible causes of hard bounces is an unverified sending domain, which means that the email domain used to send emails from Marketing Cloud Account Engagement is not authenticated and verified by Marketing Cloud Account Engagement. An unverified sending domain can result in the email servers rejecting the emails as spam or phishing attempts. To avoid hard bounces and improve email deliverability, the marketer should verify the sending domain in Marketing Cloud Account Engagement by following the steps in the reference link. Forward count, skimmed percentage, and total queued are not deliverability metrics that could indicate an unverified sending domain. Forward count measures how many recipients forwarded the email to another person. Skimmed percentage measures how many recipients opened the email for less than two seconds. Total queued measures how many emails were waiting to be sent from Marketing Cloud Account Engagement. These metrics are not related to the email domain verification or the email delivery failures. Reference Verify Your Sending Domain

According to the Salesforce documentation, the recommended way to change the scheduled send date for the email is to edit the scheduled email, select Wednesday for the new date, and save it. A scheduled email is an email that is set to be sent at a future date and time. A scheduled email can be edited or canceled before the scheduled send time. To edit a scheduled email, the user can go to the Scheduled tab in Email Studio, select the email, and click Edit. The user can then change the send date and time, as well as other settings, and save the changes. Editing the engagement studio program, deleting the engagement studio program, or deleting the scheduled email are not the recommended ways to change the scheduled send date for the email, as they are either unnecessary, ineffective, or irreversible actions. References: Salesforce documentation