Consider the following multiple linear regression model: earnings = be + b1 height + ()2 weight + b3 age + b4gender + bwearsofeducatz'm + 6. Earnings is dened as the individual's annual labor earnings, which is measured in US dollars. Height is the individual's height, measured in inches. Age is the individual's age, measured in years. Gender is the individual's gender. Years of education is the individual's years of education. Suppose that the 95% condence interval for b5 is [230, 470]. Which of the following statements is true? b5 is not statistically different from 0 at the 5% level; an additional year of education has no effect on earnings. b5 is statistically different from 0 at the 5% level; an additional year of education leads to an increase in earnings. 115 is statistically different from 0 at the 5% level: an additional year of education has no effect on earnings. by, is statistically different from O at the 5% level; an additional year of education leads to a decrease in earnings