Which of the following statements provides the best guidance for model building? if the value of r2 increases as more variables are added to the model, the variables should remain in the model, regardless of the magnitude of increase. if the value of the adjusted r2 increases as more variables are added to the model, the variables should remain in the model. if the value of r2 increases as more variables are added to the model, the variables should not remain in the model, regardless of the magnitude of the increase. if the value of the adjusted r2 increases as more variables are added to the model, the variables should not remain in the model.