多选题 From the 1900's through the 1950's waitresses in the United States developed a form of unionism based on the unions' defining the skills that their occupation included and enforcing standards for the performance of those skills. {{U}}This "occupational unionism" differed substantially from the "worksite unionism" prevalent among factory. workers.{{/U}} Rather than unionizing the workforces of particular employers, waitress locals sought to control their occupation throughout a city. Occupational unionism operated through union hiring halls, which provided free placement services to employers who agreed to hire their personnel only through the union. Hiring halls offered union waitresses collective employment security, not individual job security—a basic protection offered by worksite unions. That is, when a waitress lost her job, the local did not intervene with her employer but placed her elsewhere; and when jobs were scarce, the work hours available were distributed fairly among all members rather than being assigned according to seniority.
The author of the passage mentions "particular employers" primarily in order to

• A. suggest that occupational unions found some employers difficult to satisfy.
• B. indicate that the occupational unions served some employers but not others.
• C. emphasize the unique focus of occupational unionism.
• D. accentuate the hostility of some employers toward occupational unionism.
• E. point out a weakness of worksite unionism.