4. World population did not reach one billion until 1804.
<span>Managers and administrators are considered blue collar workers
False
People who work in jobs that require many years of education and training, and in which the work tends to be more mental than physical, are referred to as white-collar workers.
Blue-collar workers perform jobs that require manual labor.</span>
D. Lack of a clearly designated successor to the imperial throne. During the decline of the empires, the succession of the throne became a contest between family members. Hope this helps.
