28.(5%) Suppose we want to investigate the relationship between the heights of students and the sport teams they belong to. Suppose we are considering four different teams from the school: table tennis, basketball, baseball, and volley ball teams. Linear regression model can be used to analyze the data collected for this end with dummy variables. How many dummy variables should we create for this model?
(A) 1
(B) 2
(C) 3
(D) 4
(E) 5