The variable manufacturing overhead efficiency variance is $2,000 favorable. The Option B is correct.
The variable manufacturing overhead efficiency variance is a measure of the difference between the actual hours worked and the standard hours allowed for the production of goods.
Variable overhead efficiency variance = Standard overhead rate * (Actual hours - standard hours)
= $2 * (24,000 - (2.5*10,000)
= $2 * 1,000
= $2,000 F
Therefore, the variable manufacturing overhead efficiency variance is $2,000 favorable.