A. The simple formula to calculate revenue is Revenue = Quantity × Price. Variances in revenue come from either variances in quantity of product sold or variances in selling price. Since the actual results are being compared with the flexible budget, there will be no difference between the numbers of actual sales volume and budgeted sales volume. The difference between the actual revenue and the flexible budget revenue can be caused only by a difference between the actual and budgeted selling prices.

B. The sales volume variance measures the impact of difference between actual and budgeted sales volume. Since the actual results are being compared with the flexible budget, there will be no difference between numbers of actual sales volume and budgeted sales volume. The total sales volume variance is zero.

C. This answer is incorrect. See the correct answer for a complete explanation.

D. This answer is incorrect. See the correct answer for a complete explanation.