What method should be used to only add valid email addresses to their list moving forward?

LenoxSoft has a Pardot form on their website that adds prospects to their monthly newsletter list upon completion. Recently, they have noticed some of the prospects on this list have invalid email addresses.

What method should be used to only add valid email addresses to their list moving forward?
A . Send an autoresponder to prospects who complete the form with a linkto click to confirm opt-in status.
B . Allow the assigned sales rep to call prospects upon form submission to confirm their email address.
C . Edit the completion action on the form to only add to the list if the email address is valid.
D . Use the list to send a permission pass email and remove all hard bounces.

Answer: A