The manager of the motor pool wants to know if it costs more to maintain cars that are driven more often. Data are gathered on each car in the motor pool regarding number of miles driven (X) in a given year and maintenance costs for that year (Y) in thousands of dollars. The regression equation is computed as: Y-60+0.08X, and the p-value for the slope estimate is 0.7. What conclusion can we draw from this study? a. Cars that are driven more tend to cost more to maintain. b. There's no statistically significant linear relationship between the number of miles driven and the maintenance cost c. The correlation between the response variable and independent variable is significant. d. The slope estimate is significantly different from zero.