What tests of difference are appropriate in the following situations ? a. Average campaign contributions (in $) of Democrats, Republicans, and independents are to be compared. b. Human resource managers and chief executive officers have responded "yes," "no," or "not sure" to an attitude question. The HR and CEO responses are to be compared. c. One-half of a sample received an incentive in a mail survey while the other half did not. A comparison of response rates is desired. d. A researcher believes that married men will push the grocery cart when grocery shopping with their wives. How would the hypothesis be tested? f. A manager wishes to compare the job performance of a salesperson before ethics training with the performance of that same salesperson after ethics training.