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An industrial psychologist is investigating the effects of work environment on employee attitudes. A group of 20 recently hired sales trainees were randomly assigned to one of four different "home rooms" - five trainees per room. Each room is identical except for wall color. The four colors used were light green, light blue, gray and red. The psychologist wants to know whether room color has an effect on attitude, and, if so, wants to compare the mean attitudes of the trainees assigned to the four room colors. At the end of the training program, the attitude of each trainee was measured on a 60-point scale (the lower the score, the poorer the attitude). Give the null hypothesis. O A) The four rooms with different colors do not all have the same mean attitude score. 0 B) The 20 sales trainees have the same attitude score. O Cl The four rooms with different colors have the same mean attitude score. 0 D) The five trainees in one room have the same mean attitude score as the five in a different room