Other than in downtown Johannesburg, the worst air pollution in the region in the year 2000 was in ...

Other than in downtown Johannesburg, the worst air pollution in the region in the year 2000 was in Soweto. The probable explanation is that in downtown Johannesburg ________, and in Soweto ________.
A) coal-fired electrical plants were the cause; automobile traffic in overcrowded areas was the problem
B) automobile traffic was the cause; automobile traffic was also the cause
C) automobile traffic was the cause; the burning of fuels in each home for heating, light, and cooking was a major contributor to indoor and outdoor air pollution
D) gasoline-powered electrical generators were the cause; trash incinerators were a problem
E) trash incinerators were a problem; gasoline-powered electrical generators were the cause