Concept:Signs of heat in female animals are linked to the reproductive cycle and mating readiness.
Explanation:Mucous discharge from the vulva, mounting other animals, and restlessness are all common signs of heat (oestrus).
Mucous discharge from the rectum, however, is not a heat sign.
It is usually an indication of sickness or digestive trouble.
Therefore, the option that is not a sign of heat is the rectal discharge.
Answer:A. Mucous discharge from the rectum.