Please help me with my hw, explanation appreciated!

7. In a multiple linear regression with n observations and p covariates, the residual ("unexplained") population variance in the outcome is estimated by the: a. 1-2 b. Total sum of squares/(n-1) c. Sum of squared residuals/Total sum of squares d. Sum of squares for regression/p e. Sum of squared residuals/(n-p-1) 8. Which statement most accurately characterizes the usefulness of the AIC statistic? a. It is equally useful for identifying effective predictive models and as a criterion for hypothesis testing in both linear and logistic regression. b. It is a tool for identifying effective predictive models that applies to linear regression but not logistic regression. c. It provides a criterion for hypothesis testing that applies to logistic regression but not linear regression. d. It is a tool for identifying effective predictive models that applies to both linear and logistic regression. e. It provides a criterion for hypothesis testing that applies to both linear and logistic regression