A researcher is investigating the relationship between the length, in centimeters, and weight, in grams, of pineapples. The researcher will select a random sample of 15 pineapples from grocery stores in a region and construct a 95% confidence interval for the slope of the population regression line, where length is the explanatory variable and weight is the response variable. When computing a confidence interval for the slope of the population regression line, which of the following is not a condition that must be checked? A. The true relationship between length and weight is linear.
B. The standard deviation for weight does not vary with length.
C. The values of weight are approximately normally distributed at each value of length.
D. The sum of the residuals is zero.
E. The observations are independent.