Answer: A. Higher union wage rates allow companies to attract more highly skilled workers.
C. Because union wages exceed nonunion wages, employees may be encouraged to work harder
D. Unions may provide information to companies about how to improve operations and eliminate problems in the work environment.
Explanation: Labour Union describes workers in general; the working class, the workforce; sometimes specifically the labour movement, organised labour.
They often negotiates as a group with employers over renumeration and work conditions. Union workers often have higher pay in wages than non-union workers with comparable education and experience which equates to them being more productive and efficient to match their pay grade. This makes option A and C correct as they often work harder to retain their jobs.
With union workers staying longer at given jobs, coupled with training programs offered by unions which tend to reduce cost for the employers, union can provide a whole lot of information about how to improve operations while eliminating work related problems.