Direct labor hours are used as the basis for applying manufacturing overhead. This past month, the direct labor efficiency variance was $400 U and the direct labor rate variance was $2,000 F. This was based on an actual rate of $18 per hour, a standard wage rate of $20 per hour, 1,000 actual hours worked and 980 standard hours expected for the amount of output. This would imply that the variable overhead efficiency variance was:

a. Favorable

b. Unfavorable

c. Not enough info to tell