List the primary subject of all the donations with a corporate sponsored giftcard.
corporate sponsored giftcard refers to payment_included_campaign_gift_card = 't'; primary subject refers to primary_focus_subject
SELECT DISTINCT T2.primary_focus_subject FROM donations AS T1 INNER JOIN projects AS T2 ON T1.projectid = T2.projectid WHERE T1.payment_included_campaign_gift_card = 't'