According to the Salesforce documentation, the two capabilities that are true for completion actions are: C) Completion actions cannot be applied directly on a landing page, and D) Completion actions do not execute on image file downloads. A completion action is an automation tool that can be used to perform an action after a prospect successfully completes a marketing element, such as clicking a link in an email, submitting a form, or visiting a web page. A completion action can be used to perform actions such as adding a prospect to a list, assigning a prospect to a user, sending an autoresponder email, or adjusting a prospect's score. Completion actions cannot be applied directly on a landing page, as landing pages do not have completion actions. However, completion actions can be applied on the forms or custom redirects that are embedded on the landing page. Completion actions do not execute on image file downloads, as image file downloads are not considered as completion events. However, completion actions can be executed on other types of file downloads, such as PDFs or Word documents. Completion actions are not applied retroactively, as they are only applied to prospects who complete the marketing element after the completion action is created. Completion actions do not apply to both visitors and prospects, as they only apply to prospects who have been identified by their email address or their Marketing Cloud Account Engagement tracking cookie. Reference: Salesforce documentation

Explanation
According to the Salesforce documentation, the user should resolve the issue of not being able to choose the specific email template when sending a new list email by editing the email template to make it available for
"List Emails". An email template is a reusable design that defines the content and layout of an email. An email template can be configured to be available for different types of email sends, such as one-to-one emails, list emails, or autoresponders. A list email is an email that is sent to a specific list of prospects, such as a newsletter or a promotion. To use an email template for a list email, the user must edit the email template and check the box for "List Emails" in the email template settings. This will make the email template available to choose when sending a new list email. Editing the list to be available for "Email Sending", "Email Templates", or editing the email template and choosing the appropriate list are not the correct ways to resolve the issue of not being able to choose the specific email template when sending a new list email, as they are either irrelevant or incorrect options for the list or the email template settings. References: Salesforce documentation

Explanation
If LenoxSoft wants to provide a list of their products on their "Contact Us" form and ask prospects to select only one product they are most interested in, they should leverage the dropdown field type. A dropdown field is a single-select field that allows the prospect to choose one option from a predefined list. A dropdown field can be used to capture information such as product interest, industry, or country. A dropdown field can also be used as a controlling field for dependent fields5. References: Marketing Cloud Account Engagement Form Field Types

Mailable Database usage is the number of prospects in an account that are opted in and can receive emails. It does not include prospects that are opted out, in the recycle bin, or have a hard bounce or do not email status. Therefore, the Mailable Database usage for the marketer with 4,000 total prospects, 3,000 of which are opted in, 500 of which are opted out, and 500 of which are in the recycle bin, is 3,000 (A). The other options (B, C, D) are incorrect because they either include prospects that are not mailable or exclude prospects that are mailable. Reference: Marketing Cloud Account Engagement - Salesforce.com

Explanation
A landing page without a form is the Marketing Cloud Account Engagement asset that an administrator would create to advertise an upcoming event's schedule without requesting information from those who visit. A landing page is a web page that can display any content, such as text, images, videos, or links. A form is a web element that can collect information from visitors, such as name, email, or preferences. A landing page with a form, a landing page with a form handler, or an email template with a form embedded into the HTML are not suitable for advertising an event's schedule without requesting information, as they all involve forms that require visitor input3. References: 3: [Landing Pages and Forms]