When Dealing with Categorical Variables in the Context of a Multivariate

Multiple Choice

When dealing with categorical variables in the context of a multivariate regression, we:

A) Include the categorical variable directly into the model and interpret the results
B) Change the categorical variable into a dummy variable (per category) and include all of the dummy variables in the regression.
C) Change the categorical variable into a dummy variable (per category) and include all but one of the dummy variables in the regression.
D) Interact the categorical variable with a continuous variable.