Which statement correctly compares Pittsburgh in 1950 to Pittsburgh in 2010 ( 1 point )
A.) By 1950 the population of Pittsburgh was about 305,000; the population of Pittsburgh was about 675,000 in 2010.
B.) Pittsburgh in 1950 had clean air; Pittsburgh in 2010 had air pollution that caused streetlights to be turned on during the day.
C.) By 1950 the population of Pittsburgh was about 675,000; the population of Pittsburgh was about 305,000 in 2010.
D.) In 1950 Pittsburgh's steel industry had collapsed; by 2010 the steel industry was dominant again.