dsm-5 includes gambling disorder as an addictive disorder, along with substance use disorders. this inclusion is: a. unique; gambling disorder is the only disorder in the category that doesn't involve a substance. b. common; there presently are seven other disorders in the category that don't involve a substance. c. unusual; gambling disorder and computer gaming disorder both were added as non-substance disorders in the category. d. unusual; gambling disorder joins computer gaming disorder as the second disorder in the category that doesn't involve a su