Lack of Exercise. Definitely the correct answer
Incubation period: In medicine, the time from the moment of exposure to an infectious agent until signs and symptoms of the disease appear. For example, the incubation period of chickenpox is 14-16 days. In biology, the incubation period is the time needed for any particular process of development to take place.
Answer:when you cough blood leaves your heart.
Explanation: I saw a video and when some one coughed blood came out of the heart.
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