Explanation
After a Contact Delete request has been processed for subscribers who have been sent an email previously, the following data would still exist in the account:
Contact-specific data at the job level. This includes data such as open rate, click rate, bounce rate, and unsubscribe rate for each individual contact who received an email. This data is not deleted because it is used for reporting and analytics purposes.
General tracking data at the job level. This includes data such as total number of sends, opens, clicks, bounces, and unsubscribes for each email job. This data is not deleted because it is used for reporting and analytics purposes. The other options are incorrect because:
Contact data in non-sendable data extensions. This includes data such as name, address, phone number, and other attributes for each contact. This data is deleted because it is not used for sending emails and it is considered personal information.
Contact data in sendable data extensions. This includes data such as email address and subscriber key for each contact. This data is deleted because it is used for sending emails and it is considered personal information.

Explanation
Impression Tracking for Triggered Sends is the report that should be used. Impression Tracking for Triggered Sends is a feature that allows marketers to track how subscribers interact with content areas within triggered emails. Impression Tracking for Triggered Sends can be enabled for any content area that uses AMPscript or dynamic content blocks. The report shows metrics such as impressions, unique impressions, clicks, and click rate for each content area