In the U. S. in the 1830s, miles of track had been laid. By the 1860s, miles of track had been laid.

a.

40,000 and 30

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.

"d. the battle of quebec began the french and indian war and the attack on fort duquesne ended it." is your answer this is because the war and attack included washington and his people.

Ibelieve the answer its true