For each problem, select the best response.

(a) Suppose a straight line is fit to data having response variable $y$ and explanatory variable $x$. Predicting values of $y$ for values of $x$ outside the range of the observed data is called

A. causation.
B. extrapolation.
C. correlation.
D. contingency.
E. None of the above.

(b) A lurking variable is

A. the true variable that is explained by the explanatory variable.
B. the true cause of a response.
C. and variable that produces a large residual.
D. a variable that is not among the variables studied but that affects the response variable.
E. None of the above.

(c) A plot of the residuals will indicate if a line is a good fit to the data if the plot

A. shows a curved pattern.
B. shows large residuals in a symmetric pattern.
C. shows increasing or decreasing spread about a line.
D. has no systematic pattern.
E. None of the above.