As the Carbon Content in Steel Increases, Its Ductility Tends

Multiple Choice

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. The standard error of the regression slope is

A) 1.507
B) 5.09
C) -3.296
D) 2.36317
E) 1.097