What Is the Total Flexible Variable Cost Variance ("Level 2")

What is the total flexible variable cost variance ("Level 2") , assuming all variable expenses are materials-related?

A) The difference between the quantity of materials that should have been used and what was actually used, valued at the standard cost per unit of material
B) The difference between the quantity of materials that should have been used and what was actually used, valued at the actual cost per unit of material
C) The difference between what the actual sales volume was and what it should have been, valued at the standard price
D) The difference between what the materials actually cost and what they should have cost, split into direct material price variance and direct material quantity variance