How has the oil industry in houston changed over time? a it is less diversified than it was 20 years ago. b it is now based on oil drilling rather than manufacturing. c it no longer converts crude oil into petrochemicals. d it now employs more white-collar workers.

The answer to the question a am pretty sure is the letter b but I may be wrong

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.