What was the purpose for the land rush? encourage western settlement take away tribal lands pay for military posts build a railroad

The purpose for the land rush was to encourage western settlement.

Unfortunately, majority of the land that white people settled on were Indian territory. These lands were initially allotted for Native Americans to reside in when they were driven away from their original territories to give way for white men settlements. 

A lot of white men coveted said lands after they saw how prosperous and bountiful the land was under the management of the Indian people. They did not think of the hardships and hard work the Indian people did in order to make the land fruitful. All they saw was the result of the hard labor and they wanted it for themselves, to the detriment of the Indian people. 

The answer to your question would be b

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.