Which of these is a symptom of tapeworm in dogs?

Visible worms around the anus is a specific symptom that indicates the presence of tapeworms in dogs. Tapeworms are intestinal parasites that can grow several inches long and often segment off, producing proglottids, which can be seen in and around the dog's rectal area. These proglottids can appear as small, white, rice-like segments that may be moving. The presence of these segments is a clear sign of a tapeworm infestation, signaling that the dog may require veterinary treatment.

The other options do not directly relate to tapeworm infections. Flaky skin can be indicative of a variety of skin conditions or allergies, excessive sleepiness could result from numerous health issues, and urinary issues usually pertain to urinary tract infections or kidney problems rather than parasitic infections like tapeworms. Hence, the specific visibility of the worms themselves is the most telling symptom in this case.