Labor unions can increase wages through:
collective bargaining
Reducing supply of labor
and increasing demand for labor
In collective bargaining, the workers can send their representatives to negotiate new working terms with employers (including work hours and increasing wages).
Reducing supply of labor would make the existing laborers become more lucrative, rare and valued. This would resulted in an increase of workers' wages.,
Increasing demand for labor can be done by improving the members' skills through courses or seminar. By having additional skills, the members can be eligible to harder and more rare job opportunities. This usually correlate with higher wages
C. They summarize conclusions about primary sources would be the best option, because these sources differ from primary sources in that they are not first-hand accounts.
Extraneous details are remarks or information contained in someone's writing that is not pertinent or relevant to the meaning or purpose of the content.
Examples of extraneous details in writing are when a writer spends too much time on certain topic or piece of information, than the paper needs. Another example is when writers describe some object for the object's sake. The details are too much and it does not add to the writing, and does not seem to be relevant.