1) (20 points) Consider the regression model: BMI, - By + 8, DogOwner, + B,GroceryStore, + ByGym, + u where DogOwner, is equal to I if an individual i owns a dog and 0 otherwise. GroceryStore, is equal to I if individual i lives within 1 mile of a grocery store and 0 otherwise, and Gym, is equal to 1 if individual i lives within 1 mile of a gym and 0 otherwise. Who forms the reference group in this regression? What is the average BMI of the reference group