It may seem perfectly harmless to toss a pet a grape or a raisin as a treat, but these can be very deadly. although the exact cause is not known, gastrointestinal problems result after a pet ingests grapes or raisins. kidney failure frequently occurs. flowering plants, when eaten by pets, can also be lethal. lilies are especially toxic to cats by causing kidney failure. azaleas and rhododendrons can lead to serious problems for dogs. vomiting, diarrhea, and central nervous system problems can result. small amounts of xylitol, an artificial sweetener used in sugar-free candy, chewing gum, cookies, and other baked goods, can cause low blood sugar and liver damage in dogs. it doesn't take much of this stuff to cause serious problems. these three paragraphs are organized a) topically. b) chronologically. c) cause to effect. d) problem to solution.