Question 3/ 13 Which is the best way to test the effect of a subject line on email open rates? 0 Add a question at the end of the email that asks about the subject line [ O Review the patterns of website trafc originating from the email ] 0 Run a test on two populations where the only changed variable is the subject line [ O Consult a respected guide on how to craft email subject lines ] 0 Conduct focus group interviews to see which subject line was most appealing