why were political machines able to retain power in u. s. cities in the late 19th and early 20th centuries?

Political machines became common in cities because basic services for citizens and new immigrants were often extremely lacking and poor in quality. By stepping in to help ameliorate these problems, political machines won influence and votes from the populace, who often had nowhere else to turn for effective help.

Your answer is b , public works

It might be the second one