If the residuals are given by reg$residuals and the degrees of freedom are given by v, what value would the following R code return? a. 0.299 b. 15.35 c. 0.3736 d. 0.2795 18. What is the R command that fits a linear model (call it reg) to predict the dependent variable 'y' using 'x1', 'x2', and 'x3'. These variables are given in the data frame called 'data'. a. reg = lm(y ~ x1 x2 x3)