Testing whether the slope of the population regression line could be zero is equivalent to testing whether:

A) the sample coefficient of correlation could be zero
B) the standard error of estimate could be zero
C) the population coefficient of correlation could be zero
D) the sum of squares for error could be zero
E) all of these

The slope of the population regression line represents the population coefficient of correlation, so testing whether the slope could be zero is equivalent to testing whether the population coefficient of correlation could be zero. Choices A, B, and D are incorrect because they do not directly relate to the slope of the regression line.