Read this excerpt from Susan Butcher and the Iditarod Trail. At the head of Kaasen's team was a handsome black dog, Balto. He was not as fast as Togo, but he was strong and steady. Although Seppala used Balto to haul freight, he did not choose him for his relay team. Kaasen had always thought Balto was a brave dog. He would be proved right.

Which clue in the text best helps a reader predict that Balto will play a heroic role in successfully transporting the serum to Nome?

The author states that Kaasen would be proved right.
The author describes Balto as a handsome black dog.
The author points out that Balto was not as fast as Togo.
The author says that Seppala did not choose Balto for his relay team.

The constant presence of diseases or infectious agents within a given geographic area or population group. it may also refer to the usual prevalence of a given disease with such area or group. it includes holoendemic and hyperendemic diseases. a holoendemic disease is one for which a high prevalent level of infection begins early in life and affects most of the child population, leading to a state of equilibrium such that the adult population shows evidence of the disease much less commonly than do children (malaria in many communities is a holoendemic disease). a hyperendemic disease is one that is constantly present at a high incidence and/or prevalence rate and affects all groups equally. so probably family history.