The letters have been delivered by the postman change into active voice​

the postman have delivered the letters

the postman has delivered the letters

the author is showing that it is the insatisfaction of basic needs that brings about the protests such as the strikes.if workers do not earn enough to buy food and feed their families and themselves in order to continue working, what is the use of working? besides, another message from the author is that of the owners of factories should be worried about ensuring their furure by having a second and third generation of workers in their industries.if they do not hear the workers demands, they will not have any more workers to make their pockets full.

the sentence that avoid faulty coordination is:

culture, which is well represented in philadelphia, plays a major role including theatre, music, and the visual arts.  

faulty coordination occurs when the writer gives equal importance two different ideas (clauses) which in fact are not equivalent. in order to correct a misplaced clause or idea, the writer can place less important or emphatic ideas in a relative clause as in the previous sentence.