A physical therapist is conducting a study on the effects of breathing exercises and quatic therapy on preoperative lunt function in in patients undergoing partial lobectomies. Subjects we randomized to one of four groups: control, breathing exercises aquatic therapy, breathing exercises and aquatic therapy. The pulmonary lung function is measured pre-operatively and modeled using MLR Y- Bo+B,XX + B,X,1 + B,X3/+* Y = pulmonary function X1... 1 if breathing only: 0 otherwise X21-1 if aquatic therapy only; 0 otherwise X31-1 if combination; otherwise 4. How would you interpret the coeficient Ba? 5. What contrast would you evaluate in order to compare the mean pulmonary function between the breathing exercise alone group and the combination (breathing exercise and aquatic therapy) group? O a. B1-B3 Ob.B2-B3 Oc. None Od. B1-B2