Why does an increase in literacy rates often accompany an increase in per capita income?

people who have higher-paying jobs often have the time available to develop literacy skills.
developing countries have higher-than-average literacy rates, which typically leads to higher income.
people who can read and who receive an education are eligible for higher-paying jobs.
developed countries often attempt to raise low literacy rates to improve income.

According to ohrp, a problem is an “unanticipated problem” when it meets which of the following criteria: unexpected, related or possibly related to the research, suggests that the research does not put the subjects or others at greater riskunexpected, related or possible related to the research, suggests the research puts subjects or others at greater riskunexpected, unrelated to the research but still occurring with a subject, suggests the research puts others at greater riskexpected, related or possible related to the research, suggests the research puts others at greater risk

Why does the united states constitution require that a national census be taken every ten years?

What is the difference between the kurds and the shia muslims? a the kurds are a religious group while the shia muslims are an ethnic group. b the kurds and the shia muslims are religious groups. c the kurds are an ethnic group and the shia muslims are a religious group. d the kurds and the shia muslims are ethnic groups.