As the carbon content in steel increases, its ductility tends to decrease. A researcher at a steel company measures carbon content and ductility for a sample of 15 types of steel. Based on these data he obtained the following regression results, which of the following statements is not true? The regression equation is Ductility =7.67 - 3. 30' Carbon Content Predictor Coef SE Coef Constant 7. 671 1. 507 5.09 0.000 Carbon Content - 3.296 1. 097 - 3.01 0 . 010 S =2.36317 R-sg =41.0% R-sq (adj) = 36.5% O A. There is 59% of the variance in ductility that is not explained by this model. O B. The slope is significantly different from zero at a = 0.05. O C. The relationship between carbon content and ductility of steel is positive at a = 0.05. O D. For one unit increase in carbon content, one can expect a 3.30 unit decrease in ductility