Quite Frequently, Residual Plots as Well as Other Plots of the Data

Multiple Choice

Quite frequently, residual plots as well as other plots of the data will suggest some difficulties or abnormality in the data. Which of the following statements are not considered difficulties?

A) A nonlinear probabilistic relationship between x and y is appropriate.
B) The variance of the error term $\varepsilon$

(and of Y ) is a constant $\sigma ^ { 2 }$
)
C) The error term $\varepsilon$
Does not have a normal distribution.
D) The selected model fits the data well except for very few discrepant or outlying data values, which may have greatly influenced the choice of the best-fit function.
E) One or more relevant independent variables have been omitted from the model.