Where can this be configured to ensure that every time the landing page is completed, the email is sent?

An Administrator wants to have a thank you email sent after the form on the “Request a Demo” landing page is submitted.

Where can this be configured to ensure that every time the landing page is completed, the email is sent?
A . Configure an autoresponder email to send as a completion action when the ‘Request a Demo” landing page has been submitted.
B . Configure an automation rule to send the email when “Request a Demo” form has been successfully completed.
C . Configure a segmentation rule to send the email when “Request a Demo” landing page has been successfully completed.
D . Configure an autoresponder email to send as a completion action when the “Request a Demo” form has been submitted.

Answer: D