The correct statement comparing Pittsburgh in 1950 to Pittsburgh in 2010 is:
In 1950 Pittsburgh’s steel industry had collapsed; by 2010 the steel industry was dominant again.
This statement is incorrect because it implies that the steel industry recovered its dominance, which did not occur. A more accurate assessment would reflect the decline of the steel industry by 2010, where Pittsburgh had transitioned to a more diversified economy.
As for the population figures, the levels cited seem to be reversed. In 1950, Pittsburgh's population was around 676,000, and by 2010, it had decreased to about 305,000, indicating a significant decline.
None of the provided statements are correct; thus, the accurate comparisons would need to reflect the decline in the steel industry and the decrease in population.