Which of the following would have resulted in a violation of the conditions for inference?

(a) If the entire sample was selected from one neighborhood

(b) If the sample size was cut in half

(c) If the scatterplot of x = appraised value and y = selling price did not show a perfect linear relationship

(d) If the histogram of selling prices had an outlier

(e) If the standard deviation of appraised values was different from the standard deviation of selling prices