It can be inferred from the passage that which of the following, if possible, would have improved education for African-Americans
A． An increased saturation of the private sector with immigrants B． The persistence of non-African American ethnic niches in certain sectors of the economy C． A respite from competition found in the immigrant-saturated private-sector D． A decline in the number of apparel manufacturing jobs available to African- Americans E． A decrease in the level of educational credentials among new immigrants