In a multiple regression the first full model is fitted with all the explanatory variables. Several of the variables are not significant. Which one of the following is the best way to proceed? Select one:
a. There is no need to remove any variables, as this will reduce the coefficient of variation.
b. Remove the variable with the lowest p-value first.
c. Remove all the non-significant variables from the model.
d. Remove the non-significant variable with the largest p-value first,