The quality-control manager of a large factory is concerned about the number of defective items produced by workers. Thirty workers at the factory agree to participate in a study of three different incentive plans to help reduce the number of defective items produced. The plans will be randomly assigned to the workers so that 10 workers received each plan. The reduction in the number of defective items produced by each worker will be recorded two weeks after the plans are implemented. Which of the following best describes why a completely random?

a. There is no blocking variable, and incentive plans will be randomly assigned to the workers.
b. There is no blocking variable, and the workers were selected at random.
c. Each incentive plan is a block and a completely randomized design is not blocked
d. Each plan will be randomly assigned to 10 pairs of workers who share a similar characteristic.
e. The number of workers participating in the study was greater than or equal to 30

The Randomized Complete Block Design (RCBD) is a standard experimental design where experimental units or subjects are grouped as blocks (also known as replicates). In RCBD, subjects within each block are randomly assigned to the experimental units within a block. RCBD is a type of design that reduces variability by controlling variation within each treatment, thereby enhancing the estimation of the treatment effects (combinations of the factor levels of the different factors).