【单选题】A healthcare executive is using regression to predict total revenues. She is deciding whether or not to include both patient length of stay and insurance type in her model. Her first regression model ...
A.
The second model is a better model.
B.
The first model is a better model.
C.
The r2 increased when additional variables were added because these variables significantly contribute to the prediction of total revenues.
D.
The adjusted r2 always increases when additional variables are added to the model.