Jo has constructed a multiple regression model and has conducted an F test of the model at a level of significance of 0.05. The model has four independent variables. The result of the F test was that the null hypothesis was rejected. Select the appropriate conclusion that can be drawn:

a. at least one of the regression coefficients is non-zero
b. the dependent variable is not related to any of the independent variables
c. exactly one of the regression coefficients is non-zero
d. all of the regression coefficients are non-zero
e. all of the regression coefficients are zero