Consider a linear regression model with just one independent variable.Of the following statements, which of them is a good reason for looking at a residual plot?

1.To see if we should consider a higher-order polynomial model

2.To see if the error variance is constant

3.To see if there are any suspicious outliers

Select one:

a.Only 1

b.Only 2

c.Only 3

d.Only 2 and 3

e.1 and 2 and 3

PLEASE HELP ASAP AND BE SURE ABOUT ANSWER:)