Explanation
You can undelete a prospect if the deleted prospect is imported into Marketing Cloud Account Engagement with the same email address or if the deleted prospect re-converts by filling out a form with the same email address. When you delete a prospect, they are removed from your Marketing Cloud Account Engagement account, but their record is not completely erased. You can restore them by importing them again or by having them fill out a form again, which will update their existing record and undelete them. However, you cannot undelete a prospect if they visit a web page, as this will not trigger any action on their record.
Answer B is incorrect because visiting a web page will not undelete a prospect, as explained above.
References: Delete Prospects, Undelete Prospects

Explanation
The two actions that can cause an anonymous visitor to convert into an identified prospect are submitting a form on a landing page and clicking on a tracked link in an email. An anonymous visitor is a person who visits your website or interacts with your marketing assets, but whose information you have not captured in Marketing Cloud Account Engagement. An identified prospect is a person whose information you have captured in Marketing Cloud Account Engagement, and whose activities you can track and measure. You can convert an anonymous visitor into an identified prospect by capturing their email address, which is used as the unique identifier for the prospect record. You can capture the email address of an anonymous visitor by:
* Submitting a form on a landing page. A form is a web element that allows you to collect information from your visitors, 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 an anonymous visitor submits a form on a landing page, Marketing Cloud Account Engagement will create a new prospect record with the information provided by the visitor, and associate the previous activities of the visitor with the prospect record4.
* Clicking on a tracked link in an email. A tracked link is a link that is modified by Marketing Cloud Account Engagement to track the click activity and redirect the visitor to the original URL. You can use tracked links in your emails, social media posts, or banner ads to measure the engagement of your visitors with your online marketing content. When an anonymous visitor clicks on a tracked link in an email, Marketing Cloud Account Engagement will append the email address of the visitor to the URL, and use it to create a new prospect record or update an existing one. Marketing Cloud Account Engagement will also associate the previous activities of the visitor with the prospect record.

In Pardot, the best tool to use for assigning prospects to a group of users based on specific criteria is an automation rule with rule groups. Automation rules allow for the creation of complex criteria that prospects must meet to trigger certain actions. In this scenario, the rule would check for prospects with a score greater than 100, a grade greater than B, completion of any form on a landing page, and a "Product of Interest" field value of either A or B. Once a prospect meets these conditions, the automation rule can then assign them to the specified group of users. This method is efficient for processing large numbers of prospects automatically and continuously, which is not as feasible with completion actions on forms or landing pages, or with a one-time use segmentation rule.

The Marketing Cloud Account Engagement prospect audit capabilities can list all the data that was obtained by Marketing Cloud Account Engagement and how the data changes as the prospect interact with your emails, website, and CRM sync. This is true because the prospect audit table displays details about changes to the prospect record, such as field changes, list changes, assignments, form errors, email opens, link clicks, page views, CRM syncs and more.

Explanation
Warming up an IP address is the process of gradually increasing the volume of emails sent from a new or cold IP address to establish a good reputation with the Internet Service Providers (ISPs) and avoid being blocked or filtered as spam. Warming up an IP address has two main benefits: increasing deliverability and building up email reputation. Increasing deliverability means that your emails have a higher chance of reaching the inbox of your recipients, rather than being rejected, bounced, or sent to the spam folder. Building up email reputation means that your IP address is recognized as a legitimate and trustworthy sender by the ISPs, and that your emails are compliant with the best practices and standards of email marketing