The bond rating of Delta Airlines lowered to "junk". That means a. Delta bond rating is definitely less than BBC and it will be less expensive for them to borrow b. Deltas bond rating is definitely less than CCC and it will be more expensive for them to borrow c. Deltas bond ratings ia definitely less than BBB and it will be more expensive for them to borrow d. Deltas bond rating is definitely less than CCC, and it will be less expensive for them ro borrow.