For the data of Exercise 12.11 use the techniques of (a) Forward selection with a 0.05 level

Question:

For the data of Exercise 12.11 use the techniques of
(a) Forward selection with a 0.05 level of significance to choose a linear regression model;
(b) Backward elimination with a 0.05 level of significance to choose a linear regression model;
(c) Stepwise regression with a 0.05 level of significance to choose a linear regression model.