At the beginning of the year, X Company expected to produce 3,500 units of its only product. Its estimate of fixed overhead was $14,000, and its estimate of variable overhead per unit was $6.67.

At the end of the year, 2,900 units were actually produced, with actual total overhead cost of $30,717.

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: $1,401

B: $1,640

C: $1,918

D: $2,244

E: $2,626

F: $3,072