A. The flexible budget variance for variable costs is the difference between the actual variable cost incurred and the budgeted amount for the actual activity. The budgeted variable cost per unit sold is $180,000 in budgeted total variable costs ÷ 6,000 budgeted units sold, or $30 per unit. Since 5,000 dresses were sold, the budgeted amount for the actual activity is $30 × 5,000, or $150,000.The actual total variable cost incurred was $145,000. Therefore, the flexible budget variance for variable costs is the difference between $150,000 and $145,000, or $5,000. The variance is favorable because the actual cost incurred ($145,000) was lower than the budgeted amount for the actual activity ($150,000).

B. This is the difference between the actual and budgeted fixed cost. However, the question asks for the variable cost flexible budget variance.

C. This is the fixed cost variance. However, the question asks for the variable cost variance.

D. The actual cost incurred was lower than the budgeted amount for the actual activity, so the variance is favorable.