Answer:
B. variable overhead efficiency variance
Explanation:
Answer option A, C, and D are incorrect. In variable overhead cost variance, we determine the difference between the actual and budgeted cost. In fixed overhead cost variance, we do not use allocation base cost. Again, in fixed overhead volume variance, we cannot use allocation base cost.
'B' is correct because the difference between the actual allocation base quantity and budgeted allocation base quantity multiplying with the standard rate states the variable overhead efficiency variance. The activity level is required to determine efficiency variance.