The owners of a large clothing manufacturing plant are considering enacting a footwear policy for employees and have started to gather data on the type of foot coverage worn and injuries. When employees sign in for their shift they now have to indicate the type of foot coverage they are wearing. The occupational health nurse on-site believes there is an association between foot injuries and the type of foot coverage worn by the employees in the plant. The nurse decides to evaluate the average number of foot injuries in those wearing open-toed shoes, closed-toed shoes, and steel-toed boots and selects an alpha of 0.05 and a power of 0.80. She is also concerned because the plant has two separate buildings and she wants to make sure her sample is representative of the population and includes equal representation from both buildings. Which of the following characterizes the study? It has two sample groups It has on sample group It has three sample groups It has four sample groups