X Company expected to produce 3,200 units of its only product. Its estimate of fixed overhead was $13,000, and its estimate of variable overhead per unit was $6.85.

Just 2,800 units were actually produced, with actual total overhead cost of $30,392.

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: $1,011

B: $1,344

C: $1,788

D: $2,378

E: $3,163

F: $4,207