At the beginning of the year, X Company expected to produce 3,300 units of its only product. Its estimate of fixed overhead was $13,000, and its estimate of variable overhead per unit was $6.93. At the end of the year, 2,700 units were actually produced, with actual total overhead cost of $29,067. What was X Company's total overhead flexible budget variance for the year [a positive number means a favorable variance; a negative number means an unfavorable variance]? A: $2,071 C: $2,644