I believe at the time, St. Petersburg was founded in order to replace Moscow, which had been destroyed at the time.
These symptoms mostly correlate towards depression.
The answer would be B , oil in Southwest Asia has created an unequal distribution of wealth ( some countries more than the others ) .
The answer is for economic/employment opportunities
Explanation:
In general, people eventually moved to urban areas because of the way society developed and the way employment opportunities emerged more in urban areas, seeking better conditions and better employment.