A company`s marketing emails are either being found in a spam folder or not being delivered at all. The security analyst investigates the issue and discovers the emails in question are being sent on behalf of the company by a third party, mail.marketing.com. Below is the existing SPF record: v=spf1 a mx -all Which of the following updates to the SPF record will work BEST to prevent the emails from being marked as spam or blocked? 

Answer options:

A. v=spf1 a mx redirect:mail.marketing.com ?all
B. v=spf1 a mx include:mail.marketing.com -all
C. v=spf1 a mx +all
D. v=spf1 a mx include:mail.marketing.com ~all

D