Which of the following is/are true concerning heteroscedasticity? a. there is no general test for heteroscedasticity that is perfectly free of any assumption about which variable the error terms are correlated with b. in order to correct for heteroscedasticity, you must have some idea of the values of i c. heteroscedasticity generally does not represent a problem with the specification of the model d. correcting for heteroscedasticity results in estimators which are BLUE e. all of the above