Because progressive reformers attacked political machines with campaigns for more efficient urban management, they were often

A.
rejected by progressive education reformers who relied on political insiders.

B.
attacked as cold and heartless by those who felt supported by the political machines.

C.
celebrated by the masses of new immigrants who felt alienated by the city government.

D.
embraced by low-level bureaucrats who wanted to profit from their government positions.

To determine the correct answer to this question, we need to understand the consequences of progressive reformers attacking political machines with campaigns for more efficient urban management.

Progressive reformers during the early 20th century sought to address the social and economic problems caused by corrupt political machines that had controlled many cities. They aimed to improve the efficiency and accountability of urban governance.

A. Rejected by progressive education reformers who relied on political insiders
This choice suggests that progressive education reformers rejected the progressive reformers attacking political machines. However, it does not directly address the consequences of the reforms, which is what the question is asking. Therefore, A is not the correct answer.

B. Attacked as cold and heartless by those who felt supported by the political machines
This choice suggests that those who benefited from the political machines attacked the progressive reformers for their campaigns. It implies that the reforms were seen as lacking empathy or understanding towards those who were supported by the existing political machines. This answer seems to align with the potential consequences of attacking political machines, so B could be a possible correct answer.

C. Celebrated by the masses of new immigrants who felt alienated by the city government
This choice suggests that the new immigrants, who may have felt alienated by the city government, celebrated the progressive reformers and their campaigns. While the reforms may have aimed to address issues faced by immigrants, there is no specific mention of their celebration. Therefore, C is not the most likely correct answer.

D. Embraced by low-level bureaucrats who wanted to profit from their government positions
This choice suggests that low-level bureaucrats, motivated by personal gain, embraced the progressive reforms. While it is possible that some individuals benefited from the reforms, this answer does not address the broader consequences of attacking political machines. Therefore, D is not the correct answer.

Considering the options A, B, C, and D, the best-fitting answer is B.