Which of the following symptoms indicate anthrax disease?

Sudden death without any visible sign of sickness is the symptom that indicates anthrax disease. Anthrax is a bacterial disease caused by Bacillus anthracis, which can affect both humans and animals. It is known to cause sudden death in animals without any visible signs of sickness, making it a dangerous disease that requires immediate attention. The other options listed are not typical symptoms of anthrax disease. Persistent coughing may be indicative of respiratory infections or diseases, abortion in the seventh month of gestation could be caused by several factors, and prolonged diarrhea may be a sign of gastrointestinal disorders.