Which of the following statements is true?

The variable overhead efficiency variance does not actually measure how efficiently variable manufacturing overhead resources were used.

The variable overhead efficiency variance measures the difference between the actual level of activity and the standard activity allowed for the actual output, multiplied by the variable part of the predetermined overhead rate.

If variable manufacturing overhead is applied based on direct labor$-$hours, it is impossible to have a favorable labor rate variance and unfavorable variable overhead rate variance for the same period.