[12 points, 2 pts each] Exercise 4.5 Name one or more graphs that can be used to validate each of the following assumptions. For each graph, sketch an example where the corresponding assumption is valid and an example where the assumption is clearly invalid. (a) There is a linear relationship between the response and predictor variables. (b) The predictor variables are independent of each other. (c) The error terms have constant variance. (d) The error terms are uncorrelated. (e) The error terms are normally distributed. (f) The observations are equally influential on least squares results.