The house sales data set used in this class has data for 9 different years. Suppose you want to create an indicator variable for each year with a value of 1 if the house was sold in that year and 0 otherwise. How many indicator variable columns will you use in your regression? Group of answer choices You should include one less indicator variable column than you have indicator variables. In this case, you should 8 indicator variable columns. You should include an indicator variable column for each year. In this case, that is 9 indicator variable columns. You should not create an indicator variable out of the years. Instead, include the numeric values in the regression